The machine supports a maximum of 4GB, and believe me it only gets marginally better with the added 1GB.
I guess Crucial also sells SSDs and Apple sells new MBPs with 16GB RAM :) - but at this juncture I hate to spend money on anything when the other supposedly more bloated OS named Win 7 works just great with 3GB - that seriously ought to be more than enough for browsing, email and occassional Word/PPT stuff.
As for the swappiness - it seems to be at least somewhat better than Lion - hasn't used up swap after 20 minutes of doing normal stuff. But the Apple ID/Password annoyance is still there - I still had to enter Apple ID / password several times during and after the installation! The last time hopefully was for iTunes. Why can't they use one single sign on?
I'd strongly recommend getting that extra 1GB if you're looking for a cheap way to boost performance (even if you have to buy 2x2GB sticks). It's not marginal by any means if your OS is swapping - it will probably be a dramatic increase in performance!
Also, regarding doctoboggan's comment about SSDs: SSDs are still an order of magnitude slower than system RAM. The reason they're so nice is because they're an order of magnitude faster than traditional HDDs, but that doesn't mean you can get away with skimping on RAM.
If you're on any of the Aluminum MacBooks (2008 included) the specs are actually under-representing what the machine can handle. My Core2 has 8GB RAM and I have yet to feels the need to upgrade other than coveting the new high res display of course. Then again I'm also still using 10.6.8 and with the issues I've heard of there's no compelling reason to upgrade yet.
