28 working days is about 6 weeks, so don't expect it to arrive any sooner than 3 weeks.
Quite a number of people phone sony and ask if their claim mail have arrive yet, the guy/lady said they don't know yet coz there's a bag of mail that have not been open.
sometimes even more. For my example, it took them 8 weeks to send GoW demo disc from playstation underground and also took more then 6 weeks for the free casino royale to arrive @ my friend's house in London.
Bought mine on the 26th and send on the 27th.
I just heard sony start processing the mail today 07/01/08. If they do first come first serve, we would expect to receive the ps3 within two weeks from now, but who knows.