How do I know if a game that I've activated is a "Low Violence Version"?

It'll say (DE) or some indicator in your account details.

http://store.steampowered.com/account/

LV versions often have a "[DE]" or "(DE)" tag in their name.

Thanks for the quick replies. Nobody would happen to know if any of the Humble Origin Bundle games have low-violence versions, would you?

the german tag of deuce-ness (it's a word now, deal with it), "[DE]" not always stands for deuce-ness.
some other regions censor stuff as well, like australia or japan. i bought and own "Dishonored (DE)" and it's uncut, so the tag alone doesn't say much.
if you wanna check it yourself, look at your account details, and if the game shows "(DE)" next to it's name, check the game on the steam homepage (!logged off!) with a german IP (unless you actually are in germany), and if says "note: low violence version", than it's low violence.

however, if you buy a game from an american retailer on american servers, which do not have a branch at countries with game censorship, than you can be pretty sure it's uncut. (which is the case at humble bundle)

Alright, tanks a bunch guys. Really helpful, that's all I wanted to know. Sorry for no hidden giveaway as thanks, but I don't have the money :c. I'll be closing this now.