If you use Git and NetBeans with a project that's been developed under Windows, Linux and Mac, you're probably used to seeing this (ignore the green stuff):
Only one of those POMs were actually modified. If you diff them, nothing has changed. It can get much worse that just a few files, every file you open will potentially show up in here. From what I can tell, this seems to be related to line-endings. There are some config values you need to set, and you can go about this in at least two ways.
Per Project
Add the following to your <project>/.git/config file. You only need to do this once per Git project you checkout.[core]
eol = lf
autocrlf = input
Global
This is what I opted for, since I always want this functionality. I prefer predictability.
git config --global core.eol lf
git config --global core.autocrlf input
You can read more about how Git converts line endings in the gitattributes(5) man page.
There's also a bug on NetBeans' bug tracker that says this has been fixed, but it's not in 7.2.1 which is the current release version.