In contrast, Tux seems a bit stuck. It's going to be hard to make him anything but cute and cuddly. A more stylized penguin would look cold and sinister.
http://people.mozilla.com/~faaborg/files/20090515-evolvingPr...
Ironically from a good article on mozilla.com, talking about how they're evolving the Firefox icon:
http://blog.mozilla.com/faaborg/2009/05/14/evolving-a-produc...
Of the examples they give Windows is notable as being the logo which has undergone the most significant changes (while still remaining recognisable).
I can honestly say, I've never looked at the logo and thought "Hey! That's a window." But that's just me.
I did a google image search for 'Tux' - I think it demonstrates the versatility of having a living character as a logo. You can put him in lots of different situations and it's still clear that he's the 'Linux Penguin'.
I smell a photoshop contest.
Whether this proves or disproves the point probably depends more on your personal definition of "cute and cuddly".
I can't picture the Windows logo playing hockey. It doesn't even have legs. (I can picture Clippy, though. Argh.)
This reminds me of an old interview with Linus saying that while he thought the Windows logo was ok (he might have said good, I don't remember), you can't really do anything with it, while you can do put Tux is all sort of situations. It was quite common to see him playing ice hockey or reading a book or whatever -- if you knew the logo (Tux) you knew it was Linux-related.