NSA is building a quantum computer to crack encryption...

NSA is building a quantum computer to crack encryption...  This is all over the news today, because it's confirmed in the documents Snowden leaked – but I'm pretty sure that basically everyone in the cryptographic community has been assuming this was the case all along (Snowden leaks or not).  Why?  Because if a quantum computer could actually be made to work, then the NSA could use it to do one of its primary jobs: reading our adversaries' encrypted communications.  So actually I'd be quite disappointed if the NSA wasn't working on a quantum computer – unless, that is, they'd proven it was impossible...