If all the rumours about nehalem are true then its going to mean some big changes:

3 memory channels on the high end. So, Corsair, Kingston, OCZ etc, will sell new triplet packs of memory? I mean if you buy two pairs, then you got extra spare?

Quad core - whats the big deal about it. And now with Hyperthreading? What are 95%+ of users suppsed to run to occupy 8 logical CPUs?

Different sockets for mainstream and high-end. Once again this will be odd for mobo makers, since you gotta design twice as many boards.
Similarly, will this mean different format heatsinks for the different sockets? Mobo compatibility issues?

Not backwards compatibliy. Well its kinda obvious. Its nice Intel lets us buy a P965 back in 2006, and use a quad core Penryn in 2008, but I guess these perks aren't guaranteed to last forever.

IPC - Ok, I've seen a lot of numbers thrown around. All the small apps that run in cache, obviously wont see impact from built in memory controller. Winrar benchmark or other bandwidth tests will continue to depend on bandwidth.. and the benefit few less cycles/ns by integration of memory controller are offset by Intel's large cache... ie bottom line you might see single digit gains in some apps.

Quad core + IGP + NB? Now seriously, do we really need huge monolithic system on a chip?