I have a Qt app that runs on OS X that has potential to go on the new Mac App Store.
I have reviewed the guidelines at https://developer.apple.com/appstore/mac/res
Using Qt is no problem at all for creating an app for the App Store. All you have to do is to make sure that you are using Qt compiled with Cocoa and not Carbon.
EDIT: I've just found that there may be an issue if your application uses Qt plugins (as this apparently makes Qt write to ~/Library/Preferences/com.trolltech.plist which is outside the 'domain' of an App Store application.)