ILSpy 2.1 is available as of now - it supports async/await decompilation:
ILSpy_Master_2.1.0.1603_RTW_Binaries.zip
ILSpy_Master_2.1.0.1603_RTW_Source.zip
A few weeks ago, Daniel blogged about the details of how decompiling async / await is implemented. If you are only interested in the results, see the below screenshot for a proof of decompilation working (on Windows 8 RP):
As a reminder: next week on Friday we'll do a Webcast on ILSpy.