From the newsletter:

Free Delivery Site-Wide only when paying with PayPal.

Offer ends 9a.m. (AEST) Monday 5 May 2008.

• Fair play policy applies: if the delivery charge is under $100 then the full amount of the delivery is free. In rare situations where the delivery charge is greater than $100, then the first $100 is free.

In my opinion, this is once again a good offer for WA customers as oo.com.au charges high shipping fees to WA.