There's much on Google's batch of April Fools: see a nearly complete list at Google Blogoscoped, though they forgot one I found, Google's new blogging platform, Google Weblogs: 'Unsure of what to post about? Just click “I’m Feeling Lucky” and we’ll “take care” of the rest!'
My favourite, however, was the announcement at Archaeoastronomy that a team of Danish alphabetologists, led by Professor Olaf Proil, have discovered the missing 27th letter of the English alphabet
