The Alpha 1.1.1 version of Minecraft has been found and archived, as well as another somewhat rare version in c0.29_01. Alpha 1.1.1 was only available for around 3 hours because of a "greyscreen" glitch, so it was considered to be the holy grail of Minecraft versions by the community. This is a historic day.
And we wouldn't have found it if it wasn't for this tweet...
If anyone is interested in the quest to find every Minecraft version not supplied by the official launcher, it seems this server
are where they're documented in detail.