After several tries I am stuck in the same place as Dandre. The best thing I got is a normal Spinner with a ICS look using drawable as him.
@Will, I tried your method but I just got a nasty exception:
04-21 17:36:55.389: I/dalvikvm(1550): Could not find method com.actionbarsherlock.internal.widget.IcsAbsSpinner.resolveSizeAndState, referenced from method com.actionbarsherlock.internal.widget.IcsAbsSpinner.onMeasure
04-21 17:36:55.389: W/dalvikvm(1550): VFY: unable to resolve static method 5040: Lcom/actionbarsherlock/internal/widget/IcsAbsSpinner;.resolveSizeAndState (III)I
04-21 17:36:55.389: D/dalvikvm(1550): VFY: replacing opcode 0x71 at 0x0141
04-21 17:36:55.389: D/dalvikvm(1550): VFY: dead code 0x0144-014b in Lcom/actionbarsherlock/internal/widget/IcsAbsSpinner;.onMeasure (II)V
04-21 17:36:55.389: I/dalvikvm(1550): Could not find method android.view.ViewGroup.onInitializeAccessibilityEvent, referenced from method com.actionbarsherlock.internal.widget.IcsAdapterView.onInitializeAccessibilityEvent
04-21 17:36:55.389: W/dalvikvm(1550): VFY: unable to resolve virtual method 2486: Landroid/view/ViewGroup;.onInitializeAccessibilityEvent (Landroid/view/accessibility/AccessibilityEvent;)V
04-21 17:36:55.389: D/dalvikvm(1550): VFY: replacing opcode 0x6f at 0x0000
04-21 17:36:55.389: D/dalvikvm(1550): VFY: dead code 0x0003-0033 in Lcom/actionbarsherlock/internal/widget/IcsAdapterView;.onInitializeAccessibilityEvent (Landroid/view/accessibility/AccessibilityEvent;)V
04-21 17:36:55.389: W/dalvikvm(1550): VFY: unable to find class referenced in signature (Landroid/view/accessibility/AccessibilityNodeInfo;)
04-21 17:36:55.389: I/dalvikvm(1550): Could not find method android.view.ViewGroup.onInitializeAccessibilityNodeInfo, referenced from method com.actionbarsherlock.internal.widget.IcsAdapterView.onInitializeAccessibilityNodeInfo
04-21 17:36:55.389: W/dalvikvm(1550): VFY: unable to resolve virtual method 2487: Landroid/view/ViewGroup;.onInitializeAccessibilityNodeInfo (Landroid/view/accessibility/AccessibilityNodeInfo;)V
04-21 17:36:55.389: D/dalvikvm(1550): VFY: replacing opcode 0x6f at 0x0000
04-21 17:36:55.389: D/dalvikvm(1550): VFY: dead code 0x0003-0017 in Lcom/actionbarsherlock/internal/widget/IcsAdapterView;.onInitializeAccessibilityNodeInfo (Landroid/view/accessibility/AccessibilityNodeInfo;)V
04-21 17:36:55.389: I/dalvikvm(1550): Could not find method android.view.ViewGroup.onRequestSendAccessibilityEvent, referenced from method com.actionbarsherlock.internal.widget.IcsAdapterView.onRequestSendAccessibilityEvent
04-21 17:36:55.389: W/dalvikvm(1550): VFY: unable to resolve virtual method 2488: Landroid/view/ViewGroup;.onRequestSendAccessibilityEvent (Landroid/view/View;Landroid/view/accessibility/AccessibilityEvent;)Z
04-21 17:36:55.389: D/dalvikvm(1550): VFY: replacing opcode 0x6f at 0x0000
04-21 17:36:55.389: D/dalvikvm(1550): VFY: dead code 0x0003-0016 in Lcom/actionbarsherlock/internal/widget/IcsAdapterView;.onRequestSendAccessibilityEvent (Landroid/view/View;Landroid/view/accessibility/AccessibilityEvent;)Z
04-21 17:36:55.389: D/AndroidRuntime(1550): Shutting down VM
04-21 17:36:55.389: W/dalvikvm(1550): threadid=1: thread exiting with uncaught exception (group=0xb67744f0)
04-21 17:36:55.389: E/AndroidRuntime(1550): FATAL EXCEPTION: main
04-21 17:36:55.389: E/AndroidRuntime(1550): java.lang.RuntimeException: Unable to start activity ComponentInfo{net.criticalpath.uitest/net.criticalpath.uitest.UITestActivity}: android.view.InflateException: Binary XML file line #26: Error inflating class com.actionbarsherlock.internal.widget.IcsSpinner
04-21 17:36:55.389: E/AndroidRuntime(1550): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
04-21 17:36:55.389: E/AndroidRuntime(1550): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
04-21 17:36:55.389: E/AndroidRuntime(1550): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
04-21 17:36:55.389: E/AndroidRuntime(1550): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
04-21 17:36:55.389: E/AndroidRuntime(1550): at android.os.Handler.dispatchMessage(Handler.java:99)
04-21 17:36:55.389: E/AndroidRuntime(1550): at android.os.Looper.loop(Looper.java:130)
04-21 17:36:55.389: E/AndroidRuntime(1550): at android.app.ActivityThread.main(ActivityThread.java:3683)
04-21 17:36:55.389: E/AndroidRuntime(1550): at java.lang.reflect.Method.invokeNative(Native Method)
04-21 17:36:55.389: E/AndroidRuntime(1550): at java.lang.reflect.Method.invoke(Method.java:507)
04-21 17:36:55.389: E/AndroidRuntime(1550): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
04-21 17:36:55.389: E/AndroidRuntime(1550): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
04-21 17:36:55.389: E/AndroidRuntime(1550): at dalvik.system.NativeStart.main(Native Method)
04-21 17:36:55.389: E/AndroidRuntime(1550): Caused by: android.view.InflateException: Binary XML file line #26: Error inflating class com.actionbarsherlock.internal.widget.IcsSpinner
04-21 17:36:55.389: E/AndroidRuntime(1550): at android.view.LayoutInflater.createView(LayoutInflater.java:508)
04-21 17:36:55.389: E/AndroidRuntime(1550): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:570)
04-21 17:36:55.389: E/AndroidRuntime(1550): at android.view.LayoutInflater.rInflate(LayoutInflater.java:623)
04-21 17:36:55.389: E/AndroidRuntime(1550): at android.view.LayoutInflater.inflate(LayoutInflater.java:408)
04-21 17:36:55.389: E/AndroidRuntime(1550): at android.view.LayoutInflater.inflate(LayoutInflater.java:320)
04-21 17:36:55.389: E/AndroidRuntime(1550): at android.view.LayoutInflater.inflate(LayoutInflater.java:276)
04-21 17:36:55.389: E/AndroidRuntime(1550): at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:207)
04-21 17:36:55.389: E/AndroidRuntime(1550): at android.app.Activity.setContentView(Activity.java:1657)
04-21 17:36:55.389: E/AndroidRuntime(1550): at net.criticalpath.uitest.UITestActivity.onCreate(UITestActivity.java:17)
04-21 17:36:55.389: E/AndroidRuntime(1550): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
04-21 17:36:55.389: E/AndroidRuntime(1550): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
04-21 17:36:55.389: E/AndroidRuntime(1550): ... 11 more
04-21 17:36:55.389: E/AndroidRuntime(1550): Caused by: java.lang.NoSuchMethodException: IcsSpinner(Context,AttributeSet)
04-21 17:36:55.389: E/AndroidRuntime(1550): at java.lang.Class.getMatchingConstructor(Class.java:643)
04-21 17:36:55.389: E/AndroidRuntime(1550): at java.lang.Class.getConstructor(Class.java:472)
04-21 17:36:55.389: E/AndroidRuntime(1550): at android.view.LayoutInflater.createView(LayoutInflater.java:480)
04-21 17:36:55.389: E/AndroidRuntime(1550): ... 21 more
I tried to add a IcsSpinner(Context,AttributeSet) constructor with default defStyle=0 ... that worked but I just a got a TextView of the first item.