no games take advantage of it yet, except gta could use a lil more than 1 gig.
however, games will soon. granted, a single 4890 might be a little bit unbalanced with 2 gigs, as, when a game uses 2 gigs a 4890 will probably be slightly slow. what about 2x4890 tho. what about 3x4890. the gpu power would be there for the upcoming games, but sadly.. if you only had 1 gb of ram, the ram would be shy.