sys-fs/sysfsutils is broken and dead upstream. Dependency on it needs to be removed so we can remove it from the tree.
I looked at the source tree and there is lots of calls/references to sysfs_* stuff scattered throughout. Also, their configure.ac suggests this is not something you can easily get rid of: AC_MSG_ERROR([Missing sysfs2 library!]) Do you want to bounce the question off of upstream?
The current usbip userspace code now lives in a userspace/ subdirectory in the kernel tree. You may want to look at that, though at first glance it seems not much different regarding sysfsutils. If you can contact upstream about this issue, that would be nice. I have been meaning to make a new ebuild now that kernel 3.0 is released, but unfortunately other things have required my attention.
I've bumped usbip to version 3.6 from the Linux source tree -> It is still using sysfsutils -> Looks like the package is abandoned by upstream (somewhat)
*** This bug has been marked as a duplicate of bug 460960 ***