Indeed it is useful. Often I have to modify 1 file and not check it in (not my limitation), and I certainly do not want to "ignore" the file, and it still needs to be in the repo. ie a config file. In p4, I would just put this "kinda ignore it" file into its own separate changelist and forget about it, so when I check my other stuff in, I will not have to remove it all the time. Good separation.

This is vital to me as well. Cornerstone is in my opinion, superior to Versions.app, but as of this moment in my evaluation, I can recommend none of them without this feature. I am comfortable on the command line, but I'd rather not use it when I don't have to..