2009 was a great year for photography. The biggest advances I see is 1) full 1080p movie introduced by Canon for its 5D Mark II, and followed by Panasonic with its DMC-GH1, and 2) usable ultra high ISO. In 2010, more manufacturers will jump on the 1080p movie wagon with their DSLRs, and high ISO performance will get even better.
Canon will likely introduce the long waited full frame EOS 3D. This will fill the gap between the 1D Mark IV and 7D. 7D prices will be lowered to around $1500CAD by mid 2010. The 7D is a nice camera but image quality, when compared to the 5D II, still leaves a lot to be desired. The 3D will get 1D IV image quality with slightly lower frames per second. Of course, we will see the 1Ds III replacement this year.
Canon will likely introduce a new Rebel can do real 1080p video at 30 frames per second. In the lens department, we will see a few new lenses that updates the existing focal lengths, and perhaps a couple of completely new designs.
The mirrorless micro 4/3 cameras has been a big hit in 2009. I think this took many manufacturers by surprise, even Panasonic and Olympus. The EP-1/EP-2 and GF1 has a big impact on Sigma's DP-2. Sigma may be forced to introduce a Foveon based micro 4/3 camera. This will only be good news for Foveon as well as micro 4/3 lovers. To some, this will be a marriage made in heaven.
Samsung as already introduced the NX10 mirrorless micro 4/3 competitor. The success of this platform is hard to guess. On one hand, it's has a larger APS-C sensor, with slightly more pixels, which may translate into better low light performance. On the other hand, the NX10 uses a completely new mount, and no one else does.
Ricoh's GX-R is an odd ball camera system, and will remain a niche product. I don't see the GX-Rs flying off the dealer's shelves any day soon, due to its radical design and high price.
To conclude, I don't think there will be any revolutionary products for 2010. We will continue to get better and more usable high ISO range and excellent image quality from all manufacturers. More cameras will have 1080p capabilities, including the only camera maker that does not have movie mode in their DSLRs--Sony.