The Rock Band Network 2.0 update brings support for Keys, Pro Keys and vocal harmonies to RBN tracks. Developer Harmonix explains that it also "lets authors customize song practice sections and gives authors greater flexibility with camera, lights, focus, and post-processing to make the greatest visuals possible." Pro Drums support will also now be mandatory.
However, 2.0 will not add support for Pro Guitar and Pro Bass. Harmonix previously explained that implementing the feature would require "substantial work" from both itself and Microsoft, and that it would be very time-consuming for track creators. Back then, in August 2010, Harmonix noted that this decision might be revisited later.
The Rock Band Network launched in March 2010 on Xbox 360, built around the instruments and features of Rock Band 2. It allows musicians to convert their own songs to Rock Band downloadable content, which has opened the doors to unconventional--for Rock Band--music such as Beethoven and tracks from VVVVVV's chiptune soundtrack.