[MBCook]

The first time I tried to open Gimp after upgrading to Mountain Lion, OS X popped up a prompt telling me that X11 was now provided by the XQuartz project, and it had a link to go download it.

Barely different from trying to run Java software and getting the "You need Java, click here to install it" dialog box.

Apple may not be releasing X11 any more, but they made sure the experience was relatively simple. And give the number of people who actually use X11 (as a percentage of Mac users) it seems like a pretty fair decision.

[smashing]

Same thing happened to me. I looked for XQuartz after the ML upgrade on my hard drive and found that it had not been uninstalled. So I ran Gimp and it requested XQuartz be installed and opened the download page. I downloaded and installed it, then I attempted to open Gimp again. The program then requested the location of XQuartz and I identified it under Utilities and Gimp started running.

Go ahead and open a bug report. I don't that this is expected behavior.