Note that that Mac OS X uses LF not CR. Mac OS 9 and older used CR.
This post is a very good explanation of line endings, but I had assumed that everyone already knew this information. I guess only old farts know it.
Two weeks ago, I was pissed off at a teammate who checked in a file used on the Windows version of our product from his Mac. When I went to edit the file in Visual Studio, I saw the line ending dialog showed here. Our source control system, like most, uses the client OS to determine the line endings. That was the first time I had seen anybody make that mistake in years. The culprit was suitably embarrassed.