We had our interview in Feb 2009 and out Oath was in March, we were asked to sign (Not the full name) on the photos during out interview and on our Oath we were asked to sign the Oath Certificate like we did on the photos.
My friend had his interview and Oath on May 2008 and they were instructed to write their complete name. Looks like the rules changed recently.
I think the new rules went into effect sometime in June of last year.
AP