I cant really say it will use SLI, or if it doesn't. Either way some of the links i posted say it will come out with SLi support/CrossFire.
Either way you should go with the Gtx 460 SLI. Either way you'll be saving money. From what i read the difference between the GTX4xx serious are only a few frames less about 2-5. I would go with the GTX 460 SLI. You will be getting more power. For FF XIV, im sure Sli support will come out. If you are really unsure of this sistuation. I would wait it out, but for the most part im positive they will release SLI/Crossfire. After all the benchmarks don't detect the 2nd GPU. So maybe the full game does support it.
The Gts 250 and GTX 460 are very similar in power consumption in my book. 'Im not even all that sure how you can do that. I just got my 250 maybe 4 months ago and this thing just came out? I'm a little disappointed, you think its worth upgrading?