A while back, LJ introduced affiliate-link-insertion code, so that (for example) non-affiliated Amazon links could earn LJ some money. Unfortunately, the code was poorly designed, and did things like replacing affiliate links used by users, and attempting to add affiliate links to completely unrelated sites due to over-generous pattern-matching (e.g. any site name ending in "bay.com").
Well, they're back - new, "improved" code which doesn't/shouldn't hijack affiliate links that users have included, and with better site-matching. Described in lots of detail here, here, here, and here.
ETA: Also, there are some nasty privacy and maybe security implications for having this extra off-site code processing links on LJ pages (also detailed in the links above).
And in other, almost completely unrelated news, I still have one Dreamwidth invite code left :-)