The same thing, the GTX 295 has no place in the market and the "notable gains" you speak of are not very notable at all.
The GTX 295 has no place between the 5870, 5970, and 5850 crossfire.
Also the 5870 is a far better deal than 2 4890s, Tom's seems to completely ignore the benefits of a single card over a dual solution:
1. Higher minimum FPS = the single card tends to be smoother.
2. Less bugs and glitches from SLI or CFX
3. Much more linear scaling instead of SLI and CFX being all over the place at times.
4. That whole cooler running and less power consumption can mean much better overclocking.
5. Since the 5xxx series is new you CANNOT ignore that they will get better with time with driver improvements, the GTX 280 went from being beaten by the 9800 GX2 to tying with it and coming out on top at times with driver improvements, however the GTX 2xx and 4xxx series are at their peaks.