[ Edit ] there was a post above ( between mhudon's post and this one ) that disappeared when the spammer who posted it got banned from the forums, his first post was okay and related to my reply below, but he then he posted a spam link in his second post on the forums so I banned him, and that deleted his post automatically. Just fyi here. [ End Edit ]
True, the only board for AMD AM3+ with PCI-E 3.0 is Asus Sabertooth 990FX/GEN3 R2.0 ( that I currently aware of ).
If you are only running a single video card then the bandwidth of PCI Express 2.0 is more than enough, even for GTX 780 Ti / Titan / R9 290X etc. so I don't think people should be all that concerned about PCIe 3.0 support unless they are planning to SLI or Crossfire 2 or more video cards. Of course if you are buying a new system or major upgrade, it is desirable to have the latest and greatest features, but one should only pay for expensive mobo like the Sabertooth 990FX is you really need the extra bandwidth that PCIe 3.0 provides.
The richest man is not he who has the most, but he who needs the least. No good deed goes unpunished...