EDIT: You can close this, I just realized that I'm an idiot. 1.4.7 obviously removed them, since it's in a different branch than the snapshots. Nothing to see here, move along.
The new Nether Quartz ore and related items (quartz, daylight sensor) were present in my game and in newly generated chunks in the Nether after 13w01a, as expected. However, since 1.4.7, they appear to have vanished from my chests, and the ore is no longer found in in the Nether. The chunk where I had mined some may have also filled in the mined space with normal Netherrack, though I'm not 100% sure about this. In addition, I had smelted some Nether Bricks, and they have vanished as well.
I looked through stitched_items.png, and the Hopper texture is overlapping the quartz, the ore, and the brick, so I'm not sure if they're just currently invisible, or if they've actually been removed from my world. I did fill a bunch of my chests with dirt, thinking that, if they were invisible, that would let me find them, but I couldn't locate them.
Rolling back to 13w01b doesn't cause the ore to reappear in the Nether, so it may have indeed been removed.
1.4.7 does not have the new items. They will come with 1.5 however.