Im soooooooo happy with my late 2009 iMac 27 I5 after 2 years. I feel no need to buy another desktop computer for at least another 3 or 4 years, maybe even more. I dont need bluray, dont need thunderbolt, dont need internal SSD (Im using one via FW800 and it feels even faster), dont need better graphics (I dont play much), dont need more processor power (seriously... I have i5 four cores... Its too powerful for surfing the web or watching movies), dont need bigger screen (27 is VERY BIG, plus the resolution cant be better), etc.
Im very happy with my purchase, which was my first Mac. I now have a Mac Mini connected to the TV and voila! Plus the iPad for surfing the web on the couch and other stuff.
The only new thing I find interesting is thunderbolt, but I have a NAS which uses ethernet, so... no need again, for a few years.
Thank god I have no more need to buy a new computer every 2 or 3 years, which I used to have like 10 years ago...