Intel are releasing a new mainstream in either Q1/Q2 (I believe Q2) for Haswell, 1150 IIRC.
Socket 2011 for the meantime is meant to be "safe", It still has IB-E to come out, but who knows from then, wouldn't surprise me to see it removed for Haswell, but Intel might surprise us, I've seen rumours of both.
AMD currently has AM3+ its next CPU is meant to be 2014 in SR (Originally 2013, but a few rumours of delays with the AMD restructuring), however, it wouldn't surprise me to see a new socket, and I certainly wouldn't take it as fact SR will come out AM3+, nor would I take it as fact that it won't.
