That depends. On most packages I just repackage them to work properly with the ROM on others I recompile. The easiest way to tell look at the "Maintainer:" field of the package info (example: 'ipkg info quake-engine'). If it is me (Bryan) or Anton we built it. On many packages source is not available, we cannot get the source to recompile, or have not had the time to recompile. The Sharp based ROMs are not a completely open so we can only do so much.
The -x at the end of the package version is the number of times it was packaged. So, on some packages like quake-engine_1.00-4_arm.ipk I repacked it several times before I was satisfied.