Currently `ebuild package.ebuild qmerge` removes the tempdir after a successful merge :( This is quite annoying because when testing some bugs in package you have to rebuild the whole package. Please add a command which merges the installed directory to the system, but doesn't delete the tempdir.
Ups.. it has now moved to FEATURES="keeptemp keepwork" :)
You can also use FEATURES=noclean to skip the clean phase entirely.