I just completed installing the SSD into my 2010 iMac 27". I was able to wedge it in nicely underneath the GPU heat sink pipe and secured it with tape.
Theres two SATA ports, you need an angled left hand sata cable (I had a right hand laying around that I used, its a tighter fit since the wire gets bent around again to flow into the correct direction toward the disks). Also, theres the superdrive SATA/power plug all rolled into one wire and then a power connection to the logic board. Its a very straight forward process. If you have ever been inside of a computer before you'll be fine just pay attention to detail and handle everything with extreme care!
I've been toying with the idea of putting a Velociraptor in the 3.5" "bay" and continuing using my Intel x25-m G2 as a boot volume... Could be awesome, or it could be noisy, or it could be noisy and awesome!