I sent an email to ROKU requesting info and received a reply they knew nothing about GBTV.
Perhaps I missed it but has there been any official announcement that ROKU will be carrying the channel and when?
Roku doesn't necessarily create partnerships with every channel developer. It has an open SDK, which is free to everyone, that can be used to create channels. Then those channels can be released as public or private channels. A 'private' channel can only be installed by putting a code into a form in your Roku owner account page on roku.com. The channel developer generally distributes the code via their webpage, forum postings, or email. For public channels, the developer submits the channel to roku for review, and if approved, Roku publishes the channel to their channel store, where you can install it directly from your Roku box on your tv.
GBTV isn't due to be released on Roku until September 12th (http://www.gbtv.com/have-a-question/what-is-gbtv/
). They will have to follow one of the above mentioned procedures prior to that to make the Roku channel available to users. So Roku may not have any more info than we do, at least until the GBTV channel developer submits the channel to Roku. And they may not make any official announcement. New channels are added to Roku almost every week. Not all of them get announced in an official way.