I am pretty sure that is still the case.
But keep in mind that OSX itself uses RAM. And if you have Photoshop, Motion, DVD Studio Pro, and iCal all open at the same time, they are all using up RAM too. Sure, you can shut everything down and ONLY run Final Cut while editing, but that gets a litte tiresome after awhile when trying to move stuff between programs.
So there IS a benefit to buying more RAM than Final Cut can handle. Of course, your budget can have more say about that than you do. We can’t all afford 16 GB of RAM. I’ve been very happy with 4.5 GB of RAM on my system, and I usually have Final Cut along with 3 or 4 other programs running at the same time.