Because we know you're on pins and needles awaiting confirmation that Sting has signed with WWE, the latest update on as much, via the latest edition of the Wrestling Observer Newsletter (subscription required but recommended), is that a deal is no longer imminent.
That may not mean much, but it may mean everything.
From the Observer:
There was a deal a few years back in place where WWE believed Sting had agreed to come in for 100 dates-this was several years back, which would be the deal where Sting talked about them coming close once, but Sting ended up not taking the deal and took the TNA deal which probably guaranteed similar money for far fewer dates, since Sting only worked TVs and PPVs and no house shows with TNA, and didn't work all TVs or PPVs.
There's no telling what Sting has in mind, or whether or not WWE still sees the same value in signing him after the events of WrestleMania 30 and Undertaker both losing his streak to Brock Lesnar and suffering a concussion in the process. Neither side is talking and while it's clear they're friendly -- Sting has done interviews for the WWE Network and has a DVD coming out later this year -- things may very well have changed since WrestleMania.
It's also possible both sides are awaiting Undertaker's decision on his future and whether or not he'll come back to work a another match before retiring.
With WWE signing a new contract with NBCUniversal, that makes it far more likely TNA will re-up with Spike TV, keeping the promotion alive, and Sting will likely always be welcomed back with open arms, assuming he wants to continue his career. That's also unclear, considering he commented not long ago that all he wants to do now is work Undertaker at WrestleMania.
Unfortunately, much of this is simply speculation and we'll continue to wait on official word from, well, anyone involved in the situation.