I have a feeling it is... I'll check...
Ok so what I found was Street Fighter II HF...

Single player, Xbox Live Multiplayer 1-2, Local Multiplayer 1-2, HD (High Definition). HADOUKEN! Choose your fighter and defeat all 12 opponents to become world champion! Recognized as one of the best games of all time, Street Fighter® II' Hyper Fighting defined the fighting genre. Now on Xbox Live Arcade, it's completely revamped with HDTV support, Achievements, Leaderboards, and multiplayer over Xbox Live. An all new "Quarter Match" mode pays tribute to the title's arcade roots. Upgrade to the full game! Unlock your ability to earn achievements and track your high scores on the Xbox Live Leaderboards.
and...

Single Player, Xbox LIVE Multiplayer 1-2, Local Multiplayer 1-2, HD (High Definition). The original MMA series is back! Super Street Fighter II Turbo HD Remix receives a whole new look while improving on the innovative fighting system of the original game. Updated with 1080p HD redrawn art and widescreen support, the game offers a unique experience that appeals to new fans and Street Fighter® purists alike.
BUT... there's no option to download it showing just yet (just some picture packs) so I'd assume that it'll be available soon.