Seen in Grenoble today:
"no wifi"... as if it was important to indicate that this area is not covered? It's not the case here, if you read the lines under that sign. Sometimes, 802.11b cannot be employed... some context prevent people from making it available and sometimes it's even worse: you're required to deactivate your wifi-enabled devices!
Also, think about the fact that I've seen this sign in France, and there were not french translation at all around it.