Woolworths have this phone available again from Wednesday at the same price as last time (page 26 of catalog):
http://www.ozbargain.com.au/node/86106
Whirlpool confirms it can be unlocked for 5 pounds:
http://forums.whirlpool.net.au/archive/2017695
Reviews show it is a pretty good value phone, for the price. Note lack of UMTS 900 which means it won't get 3G service on Voda/Optus outside major centers.
Pretty sure Voda uses UMTS 850. It's only Optus that uses 900.