I thought they were banned network-wide, but I just edited a link out of an answer here on Web Apps.
For those not in the know, they're both a rather snarky way to—via animation—show someone how trivial their question was to search for in one of the big search engines.
Now, I get annoyed at lazy question-askers, too, but considering web search is well within our bailiwick here and some people genuinely have trouble with it, it seems to me that the last thing we want to do is turn people away by passive-aggressively calling out their lack of search skills.
According to Ban LMGTFY links across the Stack Exchange network Jeff Atwood says that there's not (currently) a way to ban links network-wide, nor would he want to use such a "big stick" approach so each site needs to decide for themselves.
Should not these sites (and similar) be banned from being linked here?