If that's the case then I wonder if my search results will end up populated solely by witticisms and novelties. In my experience so far +1 seems mainly used as a polite nod or chuckle, because its primary effect is that it's visible to the person who said the thing you approve of. Something like del.icio.us seems much more likely to identify timeless great content worth sharing -- it's a bookmark to come back to rather than a nod of social approval.

If you were designing a search algorithm it does not seem like you want want to give much weight to an embedded easy approval button (reddit, digg, +1, like, etc.) compared to something that requires more investment of someone's time and thought, like making a del.icio.us bookmark. I mean, half the time you have to go try to remember what your password was, then have them send you a password reset mail, then re-login -- now that's a bookmark I care about.