I've just got an iPhone 4s running iOS 5.01. It works fine with my 2007 XK (VIN B11139).

For info only really.

 

Does that include downloading your contacts

 

Yes.

 

An update - my iPhone asked to update to iOS5.1 this morning. I took the risk as it is still within the 14 day return period and figured if it didn't work I'd take it back and get another on iOS5.01

Anyways, it all works fine.

Again, my XK is a 57 (i.e. Sept 2007 - March 2008) plate. VIN B11139

 

My I-Phone 4S works fine in my 2008...

 

I've found my iPhone 4S to work much better than the 3GS it replaced. It's working with bluetooth much faster and more reliably.