I am moving into the research phase for this little gem, and I can second the fine effort DK put in on the review. There is not much to dislike for such a 'cost-effective' camera, and plenty of terrific high end design features. What caught my eye in particular was the focus accuracy, and excellent EVF/LV implementation in such a broad market spectrum product.
dh, apparently the A55 is outselling the A580 by three to one...certainly a pivotal camera, and one can only guess at the forthcoming A77. For the money, however, 440 grams weight (500g with the small battery - a minor whinge), 16Mp sensor, GPS, lots of built-in image production assistants, SS body and slow shutter speed capability, and reportedly great image quality make this one a terrific camera with which to enter the A mount system. Not to mention full AF video. A definite winner. Note most of these capabilities are high on the 'serious photographer' wishlist...Michael Reichmann liked it also.
You may not get an A780...how about an A99 with 30Mp?