Some BD-Live content has come (and some has gone, apparently) for those who load the English menu...
As of tonight, the "what's new" page says that from 26 Mar - 22 Apr the "opening day stage greetings" were available.
They also added the episode storyboards to page through (46MB; 141 pages, usually with two per page) on 26 Mar, but access to them appears to end on 27 May (well, "available for viewing until ..." are their words).
On 23 April, they added an audio commentary for the episode. Production people mentioned in the description are "Kazuhiro Furuhashi (director), Yasuyuki Muto (script), Shinya Ogura (conceptual consultant), Harutoshi Fukui (story [writer of the Unicorn novels, according to ANN]), Naohiro Ogata (producer)". It's a 146MB download, and currently has no cut-off date.
A teaser says that a cast commentary (Japanese, I presume, but maybe they'll do an English one for our market?) will be part of the next update on 28 May.
Going to look at the Japanese side, it doesn't look like there's anything new in the "Special Content" section. I do see three trailers flagged as "New" in the "Information" section. One is a 32 sec "Break Blade"/"Broken Blade" trailer. There's also one for something on DVD/BD/UMD that's Code Geass-related (music, pictures, and cast and/or crew on stage). The third flagged trailer is for something VOTOMS, runs for only about 20 seconds, and replaced a previous trailer.