Usability 
SociallyGiven.com has posted a piece titled 7 Versions of 'Digg Mobile' Compared which is a nice wrap up with screenshots of some of the current mobile Diggs - including five I hadn't seen before. The nicest of the new crop seems to be Original Signal, Transmitting Digg, digg.originalsignal.com/mobile which shows a reasonable 10 headlines per screen with the links to the Diggs going through Google's transcoding proxy. Unlike the most of other new Mobile Diggs, this one has small enough page sizes to will work well on any mobile.
Aug-2012: redirects to apple.originalsignal.com/mobile