I've been trying out Emacs 24 (pretest 24.0.95.1) on OS X Lion for the past few days but am running into some issues with the new gdb/MI interface.
With GDB 6.3 that comes with Xcode, but the gdb/MI interface doesn't seem to load at all. It appears to try to start the GDB GUD mode, but no commands actually work.
I also attempted installing GDB-7.4 via Homebrew. That gets me partly there. the gdb-many-windows interface shows up, but the gdb prompt never arrives. Emacs just sits there eating up 100% CPU, but yet doesn't become unresponsive. I can still open files, etc. I just can't do anything with GDB.
Has anyone else run into similar issues? Were you able to resolve them, and if so, how?
Edit: 2012-06-10: I just tried again with the newly released Emacs 24.1. The behavior with GDB 6.3 (via Xcode) remains the same. GDB-7.4 is slightly worse in that it starts up GDB, and emacs uses up 100% CPU but now I'm unable to do anything else. Emacs if frozen :/