Can git be integrated with Xcode?

Xcode 4 supports git natively (Developer Tools State of the Union Address at WWDC 2010)

Learn more here: What's new in Xcode 4
The documentation from Apple is lengthy, but a good read.

NOTE: despite all the up-votes, this answer is out of date as of June 2010

There's no git support within Xcode, but that's no reason not to use git for your Xcode projects. I've had good results managing my Xcode projects using the standard git command line or GitX.

Shane Vitarana has a nice set of .gitignore settings to use as a starting point.

A nice way to "Integrate" git with Xcode is to use DTerm. You bring up DTerm in a floating window with a key combination. DTerm knows the full path to the current document in the editor.

For Example to run a diff on the file you are editing you:

1) Press Ctrl-Return to bring up the DTerm window. (This key combo is configurable).

2) type 'git diff cmd-shift-V'. That will overwrite the last command when you start typing and insert the name of the current file in the window. Since your working directory is set to the parent directory of the selected file the command is nice and short.

I have no connection at all with Decimus. I am just a satisfied user who has run thousands of commands through DTerm.

Edit: As of 27 August 2009 DTerm is free. If you bought your copy of DTerm, the upgrade to the next version is free, regardless of when you purchased DTerm. See their blog post

Edit 2: DTerm is now available on the Mac App Store. It will be interesting to see if they kept the promise that they made in their blog post.