Intel will be launching a cut-down version of it's P45 chipset, which will go under the the name of P43. It looks like it will be quite a different chipset, in more than one way. First of all, it will lose the support for dual x8 slots that the P45 chipset will offer, but this is only an issue if you are considering adding a pair of graphics cards to your system.
However, it appears as if the P45 chipset will be DDR3 only, while the P43 remains compatible with both DDR2 and DDR3. While the P45 chipset offers official support for DDR3 memory up to 1,333MHz, the P43 chipset stops at 1,066MHz, although this seems to apply to DDR2 memory as well, which could make this an interesting platform for overclockers.
The P43 will, of course, be priced a fair bit less than the P45, but it looks like it's more of a direct replacement for the current P35 chipset, with the P45 becoming the bridge between the high-end X48 chipset and the current P35, for those looking at a slightly more affordable dual x16 slot solution.