In a Cooca Application the MainMenu.xib is setup for you in the standard template. This nib has been setup with the application delegate too. In the info.plist the key \"Mai
This is possible, but seldom worth the trouble IMO. If you have a bundle already there is little cost in including a small nib file (menu only; no window). If you want to load the rest of your UI from a separate nib file after launch, that's fine. But I recommend allowing MainMenu.nib to load and provide the main menu. (You're not clear on what problem you're trying to solve with your approach.)
That said, Lap Cat wrote a series of articles on this called "Working without a nib" that's worth reading. You'll want the last article The Empire Strikes Back where he includes the link to his nibless project. His technique still works in 10.7.