Here's a nice comparison between Sony's Super-LCD (as used in the HTC desire now) and Samsung's AMOLED and Super-AMOLED displays.

The conclusion: "all the displays were really good, they all had decent color and respectable viewing angles. The super AMOLED was noticeably less reflective than the others and was blacker with the best viewing angles. Super LCD had similar detail in the rock face video and had a superior horizontal viewing angle compared to a regular AMOLED display. The AMOLED had slightly better blacks (you can't tell from the video - sorry) and slightly better vertical viewing angles. Both Super LCD and AMOLED were very reflective."