I dropped my resume on my school website and applied on the PwC website in January. There was no cover letter required (although you were allowed to submit "additional documents"). I received a first-round interview, went to a pre-interview mixer to pick up some insider views on "why PwC" and stuff like that. Went through first rounds, sent a follow up RIGHT after (they deliberate on you the same day they choose you so make sure you send it RIGHT AWAY!), and didn't make round 2 for GPA reasons. :(