The stack trace is this:

"Worker-3" prio=5 tid=0x0113cec0 nid=0x19cb600 runnable
[0xb092d000..0xb092ed10]
        at java.lang.ClassLoader$NativeLibrary.load(Native Method)
        at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1751)
        - locked <0x24bb44b8> (a java.util.Vector)
        - locked <0x24bb44d0> (a java.util.Vector)
        at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1668)
        at java.lang.Runtime.loadLibrary0(Runtime.java:822)
        - locked <0x24bb3800> (a java.lang.Runtime)
        at java.lang.System.loadLibrary(System.java:992)
        at
sun.security.action.LoadLibraryAction.run(LoadLibraryAction.java:50)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.awt.Toolkit.loadLibraries(Toolkit.java:1509)
        at java.awt.Toolkit.<clinit>(Toolkit.java:1530)
        at java.awt.Color.<clinit>(Color.java:250)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:164)
        at
org.openquark.cal.eclipse.core.CALEclipseCorePlugin.start(CALEclipseCorePlu gin.java:
107)
        at org.eclipse.osgi.framework.internal.core.BundleContextImpl
$2.run(BundleContextImpl.java:999)
...

it looks like a manifestation of this problem:
https://bugs.eclipse.org/bugs/show_bug.cgi?id=67384#c29

I fixed it by defining the system property apple.awt.usingSWT as true
-- see https://bugs.eclipse.org/bugs/show_bug.cgi?id=67384#c127

Just to make sure -- are you still having the problem with 1.5.0?
... and if not, are you having to do anything special (such as
defining system properties) to work around the problem?

There were two problems -- the one I originally reported had the
symptom that a timeout was reported in the log file. This hasn't
happened to me on 1.5.0. The second problem has the symptom that a
thread dump shows loadLibrary hanging while initialising awt, in
response to a Color instance being created. I've only seen this on
1.5.0.

To fix the second problem I added the line:
-Dapple.awt.usingSWT=true
to the end of the file /Applications/eclipse/Eclipse.app/Contents/
MacOS/eclipse.ini

My Java version is:
java version "1.5.0_07"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_07-164)
Java HotSpot(TM) Client VM (build 1.5.0_07-87, mixed mode, sharing)