OK so this is breaking news and there aren't many details out yet. But apparently, Microsoft has made an offer to buy Yahoo! for about $44.6bn. They're valuing the web firm at about 60% more per share than the current price, which obviously makes this a staggering move. If it goes ahead (would it be allowed?!), this is the biggest story to hit the web since forever.
It looks to me like this might just go ahead. They've obviously already talked about it.
By the way: I work in this industry and I'm genuinely worried by what this might mean. For various language-related reasons, there's a good chance that plenty of programmers could go jobless if this mega-monopoly deal goes through.
More news as it comes..
Update: Here's the text of the letter Steve Balmer wrote to Yahoo (after the fold):