Image via Digital Sky via Stuarts tweet

French amateurs have reported a supernova in M51 (2 June 2011 at 00:52 UTC). Details (in French) and images here.

It's a Type II supernova, more details here. Sadly, all the GRAS telescopes are offline at the moment (curse you daylight).

Update: The Sun has set in Spain and Pete Poulous Sends this image of M51 taken with GRAS-07 using a a 300 sec luminance exposure.