What, you mean you didn't read about this in your local newspaper?
Even the New York Times mentioned this... deeply buried in the very last paragraph of a 13 paragraph article where the other 12 paragraphs were about pro-Bin Laden rallies in Cairo. And even in the 13th talks as much about the English Defense League counter-rally as about this one.
Call me crazy, but I think a pro-Bin Laden rally in London is a bit more newsworthy than one in Cairo.
The only other news outlets to mention these signs and the mock funeral for Bin Laden in London are the Daily Mail and London Metro, with a Fox News blog quoting the Daily Mail.
(h/t Alex)