Dragon's Lair is coming soon to Xbox Live Arcade, assuming that a recently posted PEGI ratings listing is accurate (via VG247). The classic coin-op arcade game/interactive cartoon is already available for a number of other platforms, but none of the other versions carry the promise of bumping up your Xbox Live Gamerscore.
The XBLA Dragon's Lair listing outs Microsoft Ireland Research as the developer. The content warnings fall in line with listings for the game on other platforms. We've reached out to Microsoft for confirmation, but it's fair to note that you typically won't see a ratings listing for one game or another until an objective set of eyes has gotten to actually look at it. Take that for what it's worth.