Is everyone on stupid pills again? How can you possibly get 20+GB back when your system and apps folder don't even add up to that size?
That's the thing. I been using monolingual to remove all the extra languages and non intel executables from my apps (which freed up roughly 3GB) and I still got back 8 gigs (converted correctly) after installing SL. A GB or two may have been swap space for me though. SL seems to keep Safari RAM usage lower for me.
NEW FIND (I think): you can quick look your print jobs from your printer list.