If I recall only four have ever done it, it came up when either Tadese or the other Geb did it about a year ago.
Solinsky has a very real chance at being the fifth man in that club. Although the half may not be his best event, I don't think it is unreasonable to think he could put down a 59:xx in 2-3 years, after London. He is probably too large to run a great marathon, what with how much more important cooling becomes, but still, I don't think the half is at all outside of his range.
Ritz also would be one to look at for this club. Although he only has one of the three times thus far, he is certainly capable of running a sub 60 half, with his 60 flat bronze medal performance, and you would have to think that if he wanted, he could scare sub 27 (although his best track years may be coming to a close soon)
The man who may have the best bet of the Americans though, is Rupp. He will run a sub 27 10k before he is done, he is too close and committed to the event. He is also going to scare sub 13 this year, even if he hasn't proven it yet. That only leaves the half marathon. Can Rupp run sub 60? Will he want too? Some people have made guesses about when Rupp was going to move to the Marathon, and I view that as an inevitability. If he makes the move after his prime, the sub 60 may never happen...
It is great to think that there are three Americans who can seriously threaten to join this elite club.
Just wanted to throw the idea out there.