In case you haven't seen it yet, Steve Winter has posted about the OSR over at Kobold Quarterly. Also check out his blog with a list of various old-school games. It's a weird feeling looking at this because not long ago I knew about all of the OSR games available, but at this point I've obviously lost track!
Where the first clones (like Labyrinth Lord and OSRIC) were about preservation, the next wave that builds on them are more about building a customized D&D from the base of what we've preserved. I think this shows the success of this movement. For example, as a supporter of open gaming I am glad to see so much text I wrote for Labyrinth Lord being recycled in Adventurer Conqueror King. Much like when variant fantasy games began to take root after D&D was released, we have more and more such games now. Of course, open game content makes it that much easier because you don't have to reinvent the wheel every time. I spent months, basically full time, writing Labyrinth Lord and the Advanced Edition Companion. I'm glad to give that text back to the open gaming community for the future of all game hobbyists.