One thing that's going in it's favor is the SEO advantage you get. This data is eventually going to play some role in the SERP rankings, one way or other. I'm not sure if it's confirmed by Google, but it apparent enough. That's incentive enough for sites to add this button.
This is something I feel like people are discounting.
+1 won't displace Liking as a _social network feature_, but it will be very interesting to see how it plays out as a _social search feature_, which is why I'm looking for how best to implement it on my own sites.
Wouldn't you be more inclined to choose a result on Google if people you know/trust +1'd it?
Yes, Google can easily rank the search results based on +1's in your social network if you're logged in. The implications are really interesting. It has to succeed though first. People have to start +1'ing for it to happen.
