If you search for Firefox using Google you’ll see this ad towards the top:
Look over to the right side and you’ll see this:
Here’s a larger complete screenshot for anyone interested.
Interesting eh? They aren’t threatened though. Here’s another tidbit. A search for “Safari” brings up a Microsoft ad as well. A search for “Opera” or “Opera Browser” does not. A search for “Browser” will. A search for “linux” will bring up a few Microsoft ads as well as a Firefox ad.