OK, so it is finally here. The T-mobile G1 is the first handset in the world to run the new Android OS. And while that is all mighty interesting, the real loser in all of this is Microsoft.

Here is why I think the mobile department in Redmond will suffer a lot from this new phone:

1) Their number one client has defected (partially); HTC has been making Windows Mobile phones for ages. They are without a doubt the biggest customer and have clearly been a little disappointed in the direction Microsoft has taken them. In recent years, they have had to do a lot of work to make Windows Mobile more attractive (TouchFlo for example). This may be just one phone, with one operator, but it does show that HTC will not sit back and stick to just one OS. The hardware used in the G1 is quite impressive, and at that price point it is even more attractive than the iPhone (albeit not as sexy).

2) The G1 is perfect for the more “hip” T-mobile customers. The kind of kids that send text messages 24/7. The kind of kids that are currently using the T-mobile Sidekick! And it just so happens that Microsoft purchased Danger (who make the Sidekick) last year! OUCH. When these kids are eligible for a contract renewal, rest assured that the G1 will be high on their must-have list. All T-mobile has to do now, is create a prepaid version.

3) Windows Mobile 7 has been delayed AGAIN. It is now on track for a late 2009 release. By then, the next iPhone will be here, Symbian S60 will be available on touch screen phones, the Android platform will be on more phones, and all Blackberry phones will have 3G. There will be very little room left for Microsoft.

4) Everything in the G1 shows how they have learned from the iPhone. From the Android applications store to the built in accelerometer. Microsoft on the other hand has learned nothing from the iPhone. You can’t deny that Apple created the basis for all future mobile operating systems. In this day and age, Microsoft doesn’t even have a decent mobile browser, and installing apps on your Windows phone is still as enjoyable as a root canal.

Of course, the G1 is not perfect; it lacks Exchange support, it has nothing for the corporate user and little is known about any of the big players working on applications for it. But I’m convinced that every mobile developer in the world is looking closely at October 22nd, and the 400,000 G1’s T-mobile plans to ship by the end of the year. With some developers in the Apple App store making $250,000 in a few months, more people will want in on similar action. If anyone can do it, Google can.