Yep, and they apparently release a ton of taint when they get destroyed.
Though, it takes more than 24 industrialcraft nukes to destroy one with an explosion, so i've no idea how to without a millenaire villager.
AHAH, wow, I didn't know it'd taint the area if the blocks were destroyed, that's kinda neat. Does the craftable tainted stone thing do this too, or to a lesser degree? Would be a neat idea for a custom map using thaumcraft. Explosion, all the weaker, craftable tainted stone is destroyed, area is suddenly tainted. Cue escape sequence/end/whatever.
While initially I thought this silly, I also thought it deserving of testing. Craftable stuff, is in fact, a different block, as expected. However, the taint-inducing, 'indestructible' one can be put in your inventory through the item mod Technic comes with. I also learned some very interesting, potentially groundbreaking info about these 'indestructible' blocks; named 'tcbhidden.' Apparently, you can put them in deployers and they will dispense them onto the ground, as with any other block. The same goes for the block breakers. Which is VERY significant, as it means if someone is able to spawn them into a multiplayer server (haven't messed with tekkit, but if it has inv edit features for anyone in there, you could have the server admin spawn it in or something), you can set up an automated system to generate a HUGE quantity of taint. How huge? This HUEG. Keep in mind that not only did this area have no taint 15 minutes ago, but it had enough aura to grow greatwood trees:
Testing also included attempting to generate the blocks with EE; unfortunately, that can't be done, so the system can't be entirely automatic. But if you fill the deployer, it won't run out until long after the area has become a zerg hive.
So to reiterate: a fully automated system, after initial setup consisting of spawning 'tcbhidden' blocks, creating a redstone repeater, creating a deployer and block breakersand hooking them to the repeater, then putting the tcbhidden blocks in the deployer, you now have a system which pumps 1.5k taint into the air every full repeater cycle. It also means you can destroy these indestructible blocks with the block breakersin technic. Science Accomplished!
Edit: currently testing whether "Fort Purity," a fort created using 4 full stacks of dawn totems and 4 full stacks of silverwood logs (and built next to a silverwood tree) can withstand the effects of the generator a bit away from it.