The Windows Phone 8 SDK went live to developers today.
Learn more: http://www.microsoft.com/en-us/download/details.aspx?id=35471 (Note it requires Windows 8)
PLUS 92% off Dev Center Account:
“Windows Phone 8 is out, the tools are available, and devices are about to be released—it’s time to get coding. As an added incentive, for the next 8 days individual developers can register for a Dev Center account for just $8 (a 92 percent savings). Please note because this is a very limited time offer. You’ll be charged $99 USD or equivalent in your local currency, and we’ll refund the difference in the next 30 to 45 days. Watch for more details on Dev Center soon.”
More information here: http://blogs.windows.com/windows_phone/b/wpdev/archive/2012/10/30/announcing-the-new-windows-phone-8-developer-platform.aspx