[citation][nom]Proximon[/nom]As our triple-posting friend brings up, there are indeed times when a single GTX 285 might be a good purchase, or even two. [/citation]
I'd disagree, the criteria to make this list is price and performance, I don't think the price of a single GTX 285 is justified at all when the 4850 X2 beats it quite soundly.
If there's a game that a single 285 beats a 4850 X2 at because of multi-GPU issues, it probably doesn't beat it by much. Conversely, the 4850 X2 can really take it to a 285 from what I've seen.
Of course I haven't benched every game under the sun, so if you have evidence of a few notable exceptions to this I'd be happy to review it and coinsider it. But without seeing that eveidence I have a hard time recommending the 285.