MrFixIt is right on the memory. Buy it from somewhere like newegg.com, and you'll save about $50. Just make sure it's the right type.
I've got the new MBP 13" 2.53GHz, and, with Snow Leopard installed, it's already the fastest 13" laptop you can get. Startup time is 33 seconds, reboot time is 40 seconds. All apps launch in under 10 seconds (I think MS Office, Photoshop CS4, and Encyclopedia Britannica take about 10 seconds, but most everything else is up in under 5). It can handle video encoding while listening to music and running a few other things in the background with only a very slight drop in speed.
Now, having said that, I have heard from several sources, that one of these with an SSD and Snow Leopard will boot up in 15 seconds. Apps supposedly launch in half the time as well. So, if you think it's worth spending the extra (plus loosing a little hard drive space), then it sounds like a good idea. I am personally going to wait until these SSDs get a little cheaper before upgrading mine to a 512GB one (that's the biggest they make right now). I expect that will take several years, though, since the cheapest 512GB one is $1500 right now ($150 more than I paid for the laptop, lol). I will buy it if it gets down to about $1-1.25/GB.