Windows Phone 7.5 (AKA Mango) has been previewed by Microsoft for months now. Numerous bloggers have been given access to early builds of it, and it’s been pretty much revealed from head to toe… or so we thought.

Today, Microsoft is officially announcing the rollout of Windows Phone 7.5. Along with that announcement comes the reveal of tethering functionality and a browser-based version of the application store which will offer an easy way to peruse the application store on a computer, much like https://market.android.com/.

Microsoft tells us that Mango updates began this morning around 10AM PST. The process is beginning gradually and will slowly ramp up — they hope to have the update available to most existing customers within 4 weeks. The update is being deployed globally, across all carriers and phones. They say that 98% of existing Windows Phone 7 devices will have access to the update when all is said and done. Kudos to Microsoft for getting the update to nearly all devices, rather than just to a specific carrier or specific phone before everyone else (*cough*Google/Android*cough*).

If you want to find out where your update is, Microsoft has a page which will give you some detail as to the status of the update for your particular carrier. If you’re on a US carrier, you’ll want to check here. International folks should give this link a try for Windows Phone 7.5 Mango update status. You’ll receive a message on your phone when the update is ready, and you’ll need to plug it into your computer for the update to commence. If you don’t already have the Zune software, or Windows Phone 7 Connector (OSX) installed, you’ll want to do that as they are required for update instillation.

If you’re looking for a final list of what will be included in the Mango update, Microsoft has a fairly extensive list of features that you’ll find in Windows Phone 7.5. If you’re a new customer and considering a Windows Phone 7.5 device, take a look at Engadget’s exhaustive review.

As mentioned, previously not revealed facets of Windows Phone 7.5 include tethering functionality and a web version of the App Marketplace. Reports indicate that tethering will only be coming to new phones with Mango installed; it’s unclear whether or not this is a software or hardware problem (my vote is on the former). The web Marketplace is already available for browsing and is part for the course — offering ratings, screenshots, top app lists, and the ability to download apps to your phone wirelessly, thanks to your phone’s association with your Windows Live account.