Yes, I’m quite sure. The Coleman BlackCat ($50; www.coleman.com) is specifically designed to heat indoor spaces. It’s OK to do this for two reasons: One, the BlackCat encloses its heat source, so that there’s no open flame to ignite nearby materials. Two, it uses catalytic technology that burns without producing carbon monoxide. The latter is, of course, the real issue with indoor heating聴carbon monoxide is tasteless, odorless, colorless, and utterly deadly, rendering you lifeless if you’re so clueless to put yourself in an unventilated space when this gas is around.
Now, having said that, keep in mind two things: One, the BlackCat does produce heat, therefore you don’t want to put it where it might get covered by a jacket or unrolled sleeping bag. It won’t ignite things quickly, but they will melt and could in time catch fire. Common sense is the key here. Two, because the BlackCat is burning propane, you will need some ventilation. Coleman recommends a six-inch opening somewhere near the BlackCat for safe usage.
Still, having said all that, the BlackCat is a reasonable thing to use in a tent, particularly a roomy one. In a little two-person tent? Still OK, but just be prudent.