I have been using 9 patch images for a while now. But have come to an issue. The GUI designer in Eclipse tells me that the image works fine. And it looks how it should.
This is definitely an issue with the latest SDK. Instructions on how to resolve this can be found here:
http://codetrips.blogspot.com/2010/12/android-draw-9-patch-seems-broken-too.html
Basically you just need to add a missing jar file into the [sdk-install-dir]/tools/lib folder.