Yes. However the profile appears to be valid one year after creation. So theoretically I could make a change that generates a new profile one day before the certificate expired and run the app for another year. I just wouldn't be able to sign a new app or renew the signing on an existing one.

At this point, noone has had their developer certificate expire. People let into the beta last year had their first year extended to sometime in June.

And as others have said, this is all only necessary if you want to develop or release an app the Apple way. The jailbreaking community has kept up for the most part, and it opens up more then Apple currently exposes. Though at the expense of instability and other issues due to the prodding in the dark.