The iMac I have is a 3.06 GHz Core 2 Duo 21.5" late 2009 model, purchased in January 2010.
HD - 1TB (factory upgrade)
RAM - 8GB ( 4x2GB after market kit upgrade)
It has been upgraded to 8GB of ram (from 4GB), and supports 16GB (which you can upgrade to for about $90 if you wanted at some point, but 8GB is plenty IMO). Has Lion installed, but can be downgraded to Snow Leopard (Discs incl Snow Leopard).
The Apple spec page is here:
iMac (21.5 and 27-inch, Late 2009) - Technical Specifications
It's in great condition— no issues now or ever with this machine. No stuck pixels, yellowing, or other cosmetic issues. No scratches, dents or scrapes. Has sat on my desk since day one, non-smoking, clean environment.
Comes with the bluetooth Apple magic mouse & keyboard, power cable, and docs+discs.
I'm in Hamilton.