There has been a leak regarding Intel's upcoming Sandy Bridge processors which tells us the new chips are rumored to be significantly faster than the current lineup, yet have a lower TDP. They will also require a new socket type: LGA 1155. And sorry, no, it will not be backwards compatible with current 1156 processors.
The details also suggest Intel will still use the current Core naming scheme, but the new products will be listed in the 2000s. The fastest processor in the Sandy Bridge lineup will be dubbed the Core i7 2600, and this CPU will have four physical cores clocked at 3.2Hz and 8MB L3 Cache. The i5 models will also have four cores, but these chips will not support Hyper-Threading. The i5 line will carry names of 2400 and 2500, and will also be clocked over 3GHz. For the low-end market, the 2100 and 2120 i3 processors will feature dual-cores with Hyper Threading support, and again the processors will be clocked over the 3GHz mark.
None of this is a dramatic shift from the current Nehalem processors, but the new chips will have a built in IGP, and the increased clock speeds will yield improved performance. The new chips will launch later this year, so the specifications can change anytime between now and launch.