I think I can provide the best input. I just got a SanDisk Extreme 240GB for my 2008 White Macbook 4,1 and I was ecstatic. One of the best reviewed SSD's on the market. I figured it would be a vast improvement and couldn't wait. However, upon installation I realized 4,1 Macbooks are SATA I not SATA II. This limits the speed dramatically. I only get ~120MB/s Read/Write speeds. Now these are decent numbers but it sucks that it's limited to SATA I. A 5400 RPM plain mechanical drive is around ~70-80MB/s Read/Write and those are VASTLY cheaper. To be honest, there's not that much real world difference. I mean things boot up a little quicker (25 seconds from desktop>restart>dekstop) but I was really disappointed I'm limited to SATA I. In my honest opinion, I would wait. Wait for a new laptop that has SATA III and by that time SSD's will be well below $0.50 a gigabyte. I say save your money and buy a bigger mechanical hard drive (7200rpm) than sink money into a SSD.
Remember I am only basing thing off the premise that you're locked to SATA I.
P.S. Apple is a real bitch on "third-party SSD's" meaning that aren't "apple approved". TRIM is a must have feature for SSD's that is why all SSD's come with it and are enabled. HOWEVER, with Snow Leopard and a third-party SSD, Apple disables TRIM. You must download a "hack" a very competent user created to enable it. It's terrible that Apple is doing this and it provides a little inconvenience but that's the way competition is.
TL;DR Save your money and just get a huge 7200 rpm, you're not going to see any real world difference between 7200rpm and SATA I unless you're doing benchmarks.