For the developers out there, you'll be psyched to know that the release candidate for the Windows Phone SDK is now available.
"The Windows Phone Software Development Kit (SDK) 7.1 provides you with all of the tools that you need to develop applications and games for both Windows Phone 7.0 and Windows Phone 7.5 devices. This download is the Release Candidate (RC) and provides a ‘Go Live’ license that enables you to develop and publish applications to the Windows Phone Marketplace."
This along with the ability for developers to submit Mango apps to the Marketplace (opening tonight) means 'go go go!' for devs out there who want to update their apps. As to what's news with the RC, you can head right here for humungo list.
Update: The RC comes in just two languages, English and Japanese. The reason for the latter, according to Shinobu Takahashi, Windows Phone developer evangelist of Microsoft Japan, is because of the high priority of getting Japanese developers to push out new apps for the IS12T, launching in two days. Thanks, tezawaly, for the heads up!