Update: My sister called Mars today ( 07/09/2008 ) and Mars told her that they reverted back to vegetarian alternative to rennet in UK (as the commenter indicated) and they never switched in US. So we can all enjoy our favorite chocolates. This proves the point that consumers can affect corporate decisions if they get together. I hope we can convince Frito-Lays to go back to vegetarian friendly rennet alternative.
According to this BBC new:
Mars/Masterfood products having best before date after 1 October 2007 would contain rennet (animal product).
Here are some of the products made by them:
Snicker’s Marathon Energy BAr