Irony: "a state of affairs or an event that seems deliberately contrary to what one expects and is often wryly amusing as a result". One would not expect a webpage condemning Facebook to suggest its readers use Facebook to promote that statement. It is wryly amusing that it does.

Not ironic in the classic sense but it is a humorous coincidence, and it says a lot about Facebook's ubiquity.

Ironic in the Alanis Morisette sense :)

It's ironic because it provides a subversion of expectations: the FTC is releasing a statement in which they are trying to demonstrate some sort of power and authority over Facebook, but at the same time using one of Facebook's product, thereby undermining (in a very minor way) their own statement. It's not deeply ironic, but it's definitely an example of irony.

Source: My partner wrote his doctoral dissertation on irony, so I happen to have picked up an appreciation for the subject.