While this may or may not be a bug, I thought it should still be mentioned.
If you rollback to an earlier version of Minecraft (1.6.2 is what I used), and you /give using the old numerical IDs, you can give yourself a technical block (I gave myself a full stone slab). And if you return to the map in 1.7.1, you will still have the technical blocks.

UNFORTUNATELY:
By rolling back to a previous version there are a few consequences:
1) Since stained glass blocks used the old locked Chest id, they will start to vanish in a corrosive manner. Glass panes will ALL disappear at entry.
2) Acacia trees will disappear like the glass panes. Dark Oak Trees appeared to have come back after re-entry to 1.7.1.
3) If ANY other blocks are removed or changed, you can't hold me accountable. Don't try this on a save that is near and dear to you...