I am fairly certain that you need to specify the apklib type in your project again even though you put it in the dependency management section. It still seems to default to the .jar when omitted.
You should only have to depend on the apklib of the library for 4.0. The support-lib jar no longer is a separate plugin and you'd only need the jar dependency for certain types of testing.
import com.actionbarsherlock.app.SherlockActivity;
public class SomeActivity extends SherlockActivity {
<repositories>
<repository>
<id>jakewharton</id>
<dependency>
<groupId>com.actionbarsherlock</groupId>
<artifactId>library</artifactId>
<version>${abs.version}</version>
<type>apklib</type>
</dependency>
<dependency>
<groupId>com.actionbarsherlock</groupId>
<artifactId>library</artifactId>
<version>${abs.version}</version>
<type>jar</type>
<scope>provided</scope>
</dependency>

Johan, Thanks for posting this.When I create a new android from the /library source, Eclipse throws me tons of errors.Any ideas?