... but the Steam version of The Last Crusade isn't the CD-ROM version that was released in 1992! LucasArts tells us that the version of The Last Crusade that will be put on Steam is a "previously unreleased version" with "even more bugfixes" than the original CD-ROM re-release, along with a "Tandy 1000 sound engine." As for LOOM and Atlantis, you'll be seeing the CD-ROM "talkie" versions for both on Steam.
The Dig was CD-ROM only, and the other six titles being released on Wednesday only had one version. The Secret of Monkey Island: Special Edition is a special case – the remastered version is obviously new, but you can switch back and forth between the "Special Edition" and the original. That "original" release is in fact the CD-ROM version of the game, not the floppy disk version, in case you were wondering.
Also of note: the copy protection system for both LOOM and The Last Crusade was to include an add-in – the "Book of Patterns" and "Grail Diary" respectively – that would have to be referenced while playing the game (take that, pirates!). LucasArts tells us they'll have PDF versions of both, so fret not, Adventure Gamer. It's your week!