I use the info at "adding to context menu" link provided by Cybercore to create a handy tool to take ownership on the fly of files and folders
I need to change permisions for whatever reasons.
You do need to excercise caution using this tool.
I wouldn't use this to take ownership of my entire C:\Windows folder for instance.
I've used it to change ownership of files and folders that I couldn't delete, something I see a lot in Win 7
and I hope is addressed in SP1 later this year.