I voted "tock," and probably won't upgrade again until a couple more rounds of "tick-tock" (i.e. sometime well after Nehalem). But even then, after reading the Tom's Hardware review of Penryn, I can easily understand why some people might decide to upgrade on this "tick." The power savings are incredible, especially when you consider that the transistor count has gone up by several hundred million.
So even though I say "tock," I can see why some people will be jumping on the Penryn bandwagon.