There are 2 aspects to consider when you discuss gaming it. The first is the effect it has on the SERPs for everybody, the second is for how it affects it for social users and what the effect on CTR is.
For the 1st, the answer is - the same way they do with links. Check for cliques, for lots of unused accounts +1'ining the same sites, etc. etc. We'll see how effective that is.
For the 2nd, one important fact is going to be you can't game people's networks. You can create a bunch of bogus accounts, and create +1 groups for circular +1'ing. However, none of that matters if you aren't in people's networks. Currently it seems that +1's only show up if at least one friend/contact has +1'd the site. Then you see the total count (see attached image), otherwise at it stands you aren't going to affect people's CTR (which itself will be a signal).
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