Look for the "HotCafé" logo: an e in a circle. Or just ask. But keep in mind that not all waiters are aware of this, you might want to ask the boss.
All of the McDonalds have it. But, rather unexpectedly, Starbucks cafés don't have it yet. Anyway, if you're in Paris, it's nicer to go to a traditional café.Very practical if you want to check your e-mail on your own computer or handheld! Or even check RATP.fr (see my post on the subject).

