Not only only well multithreaded apps.I really enjoy doing multiple things at once since i got 4 cores.Encoding a movie, ripping a movie and playing dragon age at the same time is really where its at ;-).Or declare 4 cores to crunching and play on another two.Damn i think i will be needing 8 cores.Theres all this plus watching 1080P x264 movies :P.
All in all every power user wants more cores.Not only workstation users.