You can leave it up to the Asian region to leak everything and anything. Over at Hermitage Akihabara a photo of what seems to be a presentation deck for sales reveals two Radeon R9 290 spec sheets. It seems AMD is planning not one but two R290 cards.
If the slide is correct then these GPUs get 2,816 stream processor based up to 1000 MHz of GPU clock, single-precision floating point performance of 5.16 TFLOP/s, and 4 GB of GDDR5 memory across a 512-bit wide memory interface, clocked at 5.00 GHz, that's 320 GB/s of memory bandwidth.
The R9 290 on its end has 2,560 stream processors up to 948 MHz GPU clocks, 4.9 TFLOP/s single-precision floating point performance.
Anyway, here's the photo that is spreading like fire over the internet as we speak (courtesy of Hermitage Akihabara).