First off, it is nice that they are trying to get code completion on the gdb command prompt in Xcode 4. But in its current state, it makes using the command prompt to investigate objective c objects nearly impossible - when I'm typing, it autocompletes the word to something I didn't want, and there is no way to undo this without manually selecting the text and removing it, then starting over.
I should probably file a bug with apple for this, but in the meantime, does anyone have a work around for this (like say, turning off auto-completion for the debugger without turning it off for code editing - I like auto-completion in obj-c because method names are so long :).