Some interesting memory benchmarks comparing the major Linux desktop memory usage. From the conclusion:
Ok, that's it. I tried quite hard to get these numbers and make sure they're usable. I however cannot rule any possible mistake and I'm obviously biased, so while I tried to be fair, I probably quite wasn't (however, since I myself was curious about the results, what would be the point of cheating?). So, in case you don't believe me or these numbers, you're free to redo this yourself, as long as you do your benchmarks somewhat correctly (it's really simple to do them incorrectly, trust me). In fact, since this is actually several months old, it would be nice if somebody tried with GNOME 2.16 and saved me the work.
On the other hand, it's nice to see that developers are taking more pains to reduce memory usage, or at least in the dev lists I watch for GNOME (2.14 and 2.16 had major focus on reducing memory use). Just because memory is cheap doesn't give you the right to use it up with poor programming.