Last year, I was able to listen to the Tour live on this site, for free: http://www.eurosport.co.uk/
Sadly, it was not Paul and Phil doing the commentary, but the accents were lovely just the same.

Don't forget to check out the official Tour site: http://www.letour.fr/
(Visit the French site occasionally, even if you don't know a word of French...you can often figure it out anyway, and sometimes the French version has things that the English version does not.)

Also...anyone else going to actually be at the Tour? Specifically stages 15 (July 17), 16 (19th) or 17 (20th), or the rest day in Pau on the 18th?