Thanks to estar (I think) for tracking down the very first online mention of the ‘Old School Renaissance’. Here it is at Dragonsfoot.
It's a bit trippy to see that discussion now, to realize that that was (apparently) the first mention of the ‘OSR’ – a term coined, appropriately enough, by an anonymous ‘guest’.
It also is worth noting that Castles and Crusades was the catalyst for the OSR. I rarely mention C&C here, and haven’t really thought about the game much since receiving the Castle Zagyg box set almost 5 years ago. Yet I was once an enthusiastic supporter of the game. It came along just as I found myself burnt out by 3.5 edition D&D (early 2005, if I recall correctly).
The failure of Castles and Crusades in the eyes of many fans of TSR AD&D and D&D was what prompted the retro-clones. It led initially to OSRIC, intended at first simply as a tool to enable people to publish 1e AD&D material without fear of legal retribution. OSRIC was soon followed by other ‘retro-clones’, such as Labyrinth Lord (B/X D&D) and Swords and Wizardry (0e D&D). Even more retro-clones and quasi-clones came along … And 8 years later, here we are.
C&C is still around, and apparently doing reasonably well, though it never came to be the preeminent OSR game. (But True20 as an ‘old school game’?!? What were people drinking back in 2005?).