Sony will officially discontinue the full frame a850 camera this summer, two years after its official announcement. Back in May B&H already listed the camera as discontinued. AP claims that the reason for the a850 departure is "because the 24.6MP camera is too similar in specification and price to the flagship Alpha 900 model". Interestingly enough, the Sony a900 (announced in 2008) was recently listed as discontinued as well on Sony’s Hong Kong website. There were some rumors that Sony may completely abandon their full frame DSLR cameras.
The a290 and a390 models (announced last year) are no longer in production.