While we wait (rather impatiently, we might add) for Mango to make its official debut others are still playing with test builds, pouring over code, and digging up interesting tidbits about Microsoft's mobile OS update. That WP7 will be getting improved HTML5 support is nothing new but, that it will specifically support in-browser audio and continue to stream even if you navigate away from the browser or lock the screen, is music (literally) to our ears. Snippets discovered in a recent Mango dump have also turned up mentions of Xbox Live Voice chat, parties, multiplayer gaming, and tighter integration with the 360 for pushing Live content to your big screen. If you hit the WPSauce source link you'll find a whole host of other fascinating things in the WP7 code, and some details about just how deeply Facebook will be tied to the OS. But, before you go, check out the video of the HTML5 audio support in action after the break.