Single
1920x1200 4xAA 8xAF - 43.6
X-Fire
1920x1200 4xAA 8xAF - 53.9
An increase of 10 FPS, as this is Crysis I think that is a decent gain, if not amazing.
Not amazing but seemingly taking the framerate to the cpu limit, not the graphical limit, with an overclocked CPU that crossfire score may have increased up to 80fps for all we know. AFAIK more recent driver sets have drastically improved crossfire scaling (and sli probably) for Crysis, at launch the gains were almost non existant or even worse than single.
why they put the resolution higher for Crossfire? they should have used the same resolutions for single and 2 cards
Dunno, you can still see the relevant info, its always faster, and in the only really completely gpu limited area(2560x1600 on the single gpu) you see a massive increase with crossfire, well not massive but 50% isn't at all bad, again approaching the fps limit(it would seem) and a 5 fps range for cpu limit under various circumstances isn't uncommon. The drivers will work slightly differently and have more/less balancing to do depending on the complexity of the scene. What I read from those numbers is anything from 50-55fps could increase a lot when under a faster cpu, so really the only easy thing to read is crossfire is always faster and in at least one situation there is pretty decent scaling.
http://www.legitreviews.com/article/734/7/ 4870x2 doesnt keep up with the 295 too well from what i can see here?

almost everyone here says it does.
Not sure why you're using a review without either card in, which will be very old driver sets, also showing one of the games ATi tends to do very badly in(company of heroes) though again I think a recent driver set offered massive performance bumps to ATi when in DX10 mode(I think dx9 wasn't that bad on ATi but dx10 in company of heroes specifically had major issues for a long time).
http://www.bit-tech.net/hardware/graphics/2009/08/10/gainward-single-pcb-gtx-295-review/4
one of the more recent reviews, couple results where the 295gtx pulls away, but not by much, almost identical performance in more games than it pulls away in and several games where you literally wouldn't be able to tell which card you were using. They really are very very close in performance in most games, the odd massively Nvidia optimised game runs better but still not badly on ATi, and vice versa, theres some games that run great on ATi cards, but still not at all badly on Nvidia cards. Considering you'd be hard pushed to tell which card you had in your system, a 4870x2 at £240, or a 295GTX for the same performance at £330-350, the choice is easy for most people.