One thing not mentioned in other answers is that some types of beans have seasoned/flavored liquid. Mostly, I tend to see this with black beans (often with a "seasoned" liquid) and so-called "chili beans," which tend to be small red beans or pinto beans in a chili-flavored liquid. (Note here that I'm not talking about actual canned chili or prepared canned dishes -- just beans that are usually found in the same section of a grocery store as "plain" canned beans.)
In those cases, I sometimes retain all or part of the liquid from canned beans, because that liquid contains other seasoning beyond salt, and I tend to use such "seasoned beans" in dishes that could benefit from such seasoning.
Otherwise, I agree with other answers -- I tend to drain and rinse all my other canned beans before using. I don't generally find the texture or flavor the liquid imparts to be helpful in most cases, even in soups, chili, etc., and getting rid of some of the gas-causing elements is useful. I know that significant amounts of vitamins and other nutrients are lost from dry beans if you toss the soak water, so I assume that's the same with draining canned beans.
(Note that in general I tend to retain soaking and cooking water when making dry beans, particularly for nutritional and flavor reasons, but the texture of the stuff in canned beans is often weird. Also, when cooking dry beans, you have the option of cooking slowly for a long time, which will tend to break down many of the gas-causing elements even if you retain the soak water. With canned beans, cooking that long will often cause the beans to get to soft and break down -- and usually I tend to use canned beans when I don't have enough time to simmer that long anyway -- so draining/rinsing is the only effective way to remove a significant amount of gas-causing components.)