It looks like when Microsoft launches Windows Phone 7, a large portion of those devices will be heading over to the Big Blue network according to a recent tweet on Twitter, perhaps AT&T is looking to use Windows Phone 7 as a replacement for the iPhone when the time comes.

According to an article over on Wmpoweruser by I3v5y, the guys over at Mobility Digest picked up on a tweet from Michael Gartenberg, who writes a business tech monthly column on Computerworld, and is ranked by TechnoBabble as amongst the top 50most influential analyst bloggers, so it’s reasonable to surmise he knows what he’s talking about.

Anyway the tweet basically said that AT&T has signed up for 8 million Windows Phone 7 devices, which if it turns out to be true it’s a serious number for the first generation of a new platform to be making a splash on the AT&T network.

Of course with all the buzz about T-Mobile USA getting the iPhone in Q3 and the constant rumours of a Verizon iPhone coming, perhaps AT&T is simply bolstering their line up in case Apple do give them the big heave-ho.