After creating a handful of Facebook applications over the past few months I have never had a problem assigning them names. It seemed that Facebook was cool enough to let you put anything there even the word Facebook. I had many sample applications like "Testing Facebook Authentication."

Today I was editing this application and when I tried to save my settings it warned me that this application name was invalid since it contains the word 'face'.

I edited this same application earlier in the week with no problems, so it looks like this is a very recent restriction.

This seems a little ridiculous to me. I can understand them not wanting people to use Facebook trademarks in their application title, but the word face?

A simple search for "facebook" in the application directory shows ten approved applications that not only use the word face, but have the whole facebook word in them. Why didn't the application review staff stop these people?

At this point it looks like your canvas URL can have "face" in it without being warned otherwise, but I suggest being careful when choosing a name and canvas URL for your application to avoid having to change it in the future.