What was in maintenance? 15/Jan/11

What was in maintenance last Saturday?
Could have support for some older scripts/functionality have ended or something?
Has anyone had changes in stats since Saturday’s maintenance window?

I’ve got a drop in page impression.

Current theory.

Google has mandatorally moved their Australian account holders from US to local currency.

By default payment type was by cheques. I think, Google wants customers on funds transfer. Since the last maintenance window, adsense has started displaying only Public Service Advertisements (PSAs) where payment type isn’t set. Thus encouraging account holders to specifically set their payment type, preferably to funds transfers.

As I understand it, PSA’s don’t generate page impressions. Is this true?

Is this theory feasible?