Windows Phone 7

Microsoft just planted a massive flag in the ground with the debut of Windows Phone 7 Series. The company's new mobile operating system is a radical and potent departure from the past, and there's a lot to take in -- so we've gathered together all our knowledge and impressions of the device so far and rolled them into a single, concise guide. Of course, there will be plenty more to learn in the coming months, and we're going to be beating down Redmond's door for more details on this thing, but for now let's dive into what Microsoft has revealed so far about its latest and (potentially) greatest phone operating system.
With Windows® Phone , connect and play with friends wherever you are, using your Xbox LIVE® avatar and gamer profile to keep track of scores and wins. You're always in the game with the only phone with Xbox LIVE built in.View, access, and launch your game library from one easy-to-navigate hub on your phone. This puts your favorite Xbox LIVE features at your fingertips so you can make the most of every moment by connecting and playing with friends wherever you go.Bring your gamer friends with you wherever you go. With Xbox LIVE and Windows Phone, you can see who’s online and what your friends are doing on their consoles, PCs, or Windows Phones.Invite and play against friends on other Windows Phones or PCs with turn-based (asynchronous) multiplayer gaming.Avatar Marketplace on your Windows Phone is new and improved! Now, you have more options to customize your Avatar with a wide range of props and clothing right on your phone to make sure your Avatar is looking its best.Access special spotlight feeds to get all the details on the latest game titles, breaking news from Xbox LIVE, game tips and tricks, and more.
Large WVGA screen with a single aspect ratio (which means BlackBerry-style devices won't be readily available to begin with)Here's a look at some of the minimum specs detailed to us thus far:

• Five specific hardware buttons required: Start, back, search (a dedicated Bing button), camera button, and power -- no more, no less
• Capacitive multitouch
• CPU and GPU requirements (beginning with Qualcomm's Snapdragon as the go-to processor)
• WiFi
• AGPS                                                                                       
• Accelerometer                                                                 
• FM radio
• High resolution camera   
• People hub
• Pictures Hub
• Music Hub
• Videos Hub
• Marketplace Hub
• Office Hub
•  E-mail
• Calender
• SMS
• Internet Explorer
• Bing Search
• Bing Maps          

Review taken from Xbox Live website and Engadget