Yeah you can no longer use HTML tags in posts nor sigs. Even before then, though, only HTML code that had a working BBCode equivalent would work, for security reasons (eg if an idiot signs up on this forum and post iframes leading to viruses or rickroll scripts)
As always, though, people have to keep their sig as small as possible (the max height that shows up at once is 150 pixels and if staff catches someone using a very large filesize animated GIF or one that flashes too much they'll remove it).
