I am attempting to use the Export Deployable Features wizard with JAR Signing options enabled.  However, this very unhelpful error is consistently generated:
{quote}
Problems during export
  C:\working\elims\dev\com.rjlg.elims.client.bundles\assemble.com.rjlg.elims.client.bundles.win32.win32.x86.xml:55: The following error occurred while executing this line:
C:\working\elims\dev\com.rjlg.elims.client.bundles\assemble.com.rjlg.elims.client.bundles.win32.win32.x86.xml:30: jarsigner returned: 1
  The following error occurred while executing this line:
C:\working\elims\dev\com.rjlg.elims.client.bundles\assemble.com.rjlg.elims.client.bundles.win32.win32.x86.xml:30: jarsigner returned: 1
  C:\working\elims\dev\com.rjlg.elims.client.bundles\assemble.com.rjlg.elims.client.bundles.win32.win32.x86.xml:55: The following error occurred while executing this line:
C:\working\elims\dev\com.rjlg.elims.client.bundles\assemble.com.rjlg.elims.client.bundles.win32.win32.x86.xml:30: jarsigner returned: 1
  The following error occurred while executing this line:
C:\working\elims\dev\com.rjlg.elims.client.bundles\assemble.com.rjlg.elims.client.bundles.win32.win32.x86.xml:30: jarsigner returned: 1
{/quote}
I'd be happy to provide more details, but I cannot find any other debugging or log output.  My ".metadata/.log" file is empty.  I see the same error while running the IDE under jdk1.5.0_10 and jdk1.6.0.  Please advise me on how I can assist in getting this resolved.

If I remember correctly this happens if the VM that is being used to run the Eclipse from which you are doing the export is a JRE and not a JDK. 
Exit, try to start eclipse with a JDK (make sure you have the jarsigner.exe in it) and then do the export.
We should see if we can run a precheck and report a nicer error message.

I can confirm that this bug is definitely NOT caused by the IDE running with a JRE instead of a JDK.  I am explicitly setting the -vm option in the Windows launch shortcut, and I have confirmed it via the Eclipse "about" dialog.
Regardless of the root cause of the export failure, there is a more fundamental issue here: there is absolutely no way to debug this issue.  No logging output is generated anywhere I can find, and none of the generated artifacts are still present after the failure.  I would love to double-check the sign command, but I have no way to access what that command might be, since it is dynamically generated and automatically deleted.
What should be my immediate next step to help you folks debug this?

I got the similar error on linux machine (Ubuntu 7.10). I tried both JRE and JDK, same error. The only difference between mine with windows OS is the file "assemble.MyBPELFeatures.linux.gtk.x86.xml". Please refer the error message for detail info. Also I can't find this file under the feature project directory! 
Any suggestion to work around this problem before the official correction?
The following is detailed error message:
Problems during export
  /home/samwzm/eclipse/eclipse33GMF/workspace/MyBPELFeatures/assemble.MyBPELFeatures.linux.gtk.x86.xml:55: The following error occurred while executing this line:
/home/samwzm/eclipse/eclipse33GMF/workspace/MyBPELFeatures/assemble.MyBPELFeatures.linux.gtk.x86.xml:30: jarsigner returned: 1
  The following error occurred while executing this line:
/home/samwzm/eclipse/eclipse33GMF/workspace/MyBPELFeatures/assemble.MyBPELFeatures.linux.gtk.x86.xml:30: jarsigner returned: 1
  /home/samwzm/eclipse/eclipse33GMF/workspace/MyBPELFeatures/assemble.MyBPELFeatures.linux.gtk.x86.xml:55: The following error occurred while executing this line:
/home/samwzm/eclipse/eclipse33GMF/workspace/MyBPELFeatures/assemble.MyBPELFeatures.linux.gtk.x86.xml:30: jarsigner returned: 1
  The following error occurred while executing this line:
/home/samwzm/eclipse/eclipse33GMF/workspace/MyBPELFeatures/assemble.MyBPELFeatures.linux.gtk.x86.xml:30: jarsigner returned: 1