The rest of Sony's DSLR refresh—the more expensive part—is here, and it's slight. Their midrange A5x0 get new, low-light-happy Exmor sensors and automatic HDR shooting. The full-frame a850 (née a900) gets almost nothing, except a $US2000 price tag.
The a500 and a550, only differentiated by their 14.2MP and 12.3MP sensors and the 550's slightly faster shooting speed (seven shots per second), inherit some of the same sensor and noise reduction technology as those Exmor-equipped point-and-shoots that David Pogue liked so much, meaning that they're probably pretty good at shooting in low light, though that claim that you can snap pictures at ISO 12800 "without sacrificing fine detail" is a little touch to swallow. Both cameras also get an easy HDR mode, which handles processing in-camera.
And no, even though they clearly should, neither shoots video.
The a850, as suspected, is more or less a carbon copy of Sony's old a900 full-frame DSLR. That's the same 24.6MP sensor, what looks like the exact same body. The only noticeable difference is that the a850 will run just under $US2000, in November, for just the body, making it a decently cheap option for someone looking for a full-frame DSLR. The a500 and a550 will ship for a decidedly less exciting $US750 and $US950, body-only, in October. [Sony]