This week, Microsoft showcased its new Windows Phone 7 platform at the World Mobile Conference in Barcelona. One part of its announcement that hasn't gotten enough attention is its decision to name AT&T its "premier partner" in the U.S. I think this is hugely significant for two reasons: it shows AT&T isn't content with just Apple and further develops alliances in the wireless industry.

Over at PC World, Tony Bradley notes how big a win this is for AT&T:

One of the most interesting things about the unveiling of the new Windows Phone 7 platform by Microsoft at the World Mobile Conference was the announcement that AT&T will be Microsoft's "premier partner" in the United States. As much flack as AT&T takes from customers and media, it is still the "chosen one" for premier smartphone platforms.

I would add that it's also impressive from a diversity of partners point of view. Not many in the tech industry can brag about holding hands with both Apple and Microsoft simultaneously. That makes up a huge portion of the mobile platform market, with the most notable competition now just phones running the Google Android platform (it already has a significant Blackberry offering). But AT&T also recently announced that it was planning on introducing some Android-based phones as well, so that might not be much of a probably either.

If you assumed that Apple was dropping AT&T, then it might make sense for the carrier to make a deal with Microsoft -- to make sure the service provider isn't left without a strong partner. But as I recently noted, Apple's choice of keeping AT&T as the iPad data provider shows that the AT&T-Apple partnership doesn't appear to be weakening. Assuming that Apple does stick with AT&T, the wireless company will be in a very strong position.

This decision by Microsoft also further delineates the alliances in the wireless industry. Now you've sort of got Verizon-Google versus AT&T-Apple-Microsoft. Of course, even then there will inevitably be some Verizon phones that run Microsoft's Windows Phone 7 and some AT&T phones than run Google's Android. But it's clear that the Verizon-Google and AT&T-Windows relationships will be stronger. Other service providers like Sprint and T-mobile aren't beaten yet, but they haven't managed to grab the attention of these big name software companies like Verizon and AT&T.

This all makes for a mobile phone market that should keep evolving quickly, due to the intense competition we're seeing between these big service providers. Just yesterday, I mentioned that Verizon has decided to work with Skype, a measure that AT&T will almost certainly feel forced to respond to. Even though the market appears to be gravitating towards a small oligopoly of just a few big names, the competition continues to be fierce.