It may seem like I usually come down hard on Microsoft software. The simple reason for that is that Microsoft software is worse than Apple software. But that doesn’t mean Apple software is flawless.
After the user double clicks a file with no extension (or any other kind of type data), Mac OS X offers a chance for the user to pick an application to use to open the file. So far so good. After clicking the application, I got this message.

If you can figure out what’s being updated, or why Cancel is different than Don’t Update, you are either the developer who wrote this useless message or have the same kind of brain damage. Either way, it’s not too late for you — seek professional help.
not seen this one after 10.4. there are strict rules in compiling dialogues on the Apple Developer site… they don’t seemed to have been followed here (or in iTunes i may add).
I think Cancel is a hangover from earlier versions of this pannel. hmm.
It is indeed 10.4; the very latest PowerPC version, as of yesterday. When I clicked Cancel, I got an obscure error message (something like “An unknown error occured, #####,” but I forget what the number was.) I never tried clicking Don’t Update, but I wonder if that would have made TextWrangler open the file but the Finder would have asked again next time. Either way, it’s a pretty pointless message.
I decided to report it in radar (4721448). I suspect like every other bug I’ve ever reported it will remain open forever or be marked Duplicate. Sigh.