Now we have all the details pertaining to Windows Phone 7 Mango. First of all, Acer, ZTE, and Fujitsu have joined in as OEM partners. Secondly is the long list of new features, which includes text-to-speech, speech-to-text, Grouping (which allows you to place contacts in a group), threaded messaging in email, SMS and Windows Live Messenger, Twitter and LinkedIn integration baked into the OS, facial-recognition software for social networks like Facebook, better Live Tiles which have more detail, multitasking/ fast app-switching (started by holding the back button), brand new Bing search, better integration of friends in the Xbox LIVE Hub, the new Internet Explorer 9 with HTML 5 support, landscape typing, access to apps, your location, a new on-screen keyboard that is smarter, and hardware acceleration.
Also, the update will be released sometimes in the early autumn, for free, for all current Windows Phone 7 devices. More details on things like multitasking and such will be posted here when the event ends. Also, Windows Phone 7 Mango Beta SDK tools will be provided to devs for free within the next 24 hours.
Update: Press release after the break. Also, the image above is the new representative of the Mango interface.