Just checked again (without actually booking) many more flights for August and September 2010, still shows as now ALL flights except one or two a day are QF mainline B737 flights, and the others are clearly shown as Jetstar flights to and from Avalon still.
IF what you are saying is true, I guess the Qantas booking site has not been updated yet.
BTW before someone gets the wrong idea (as usual here) my earlier comment about we NEVER use Jetstar is because we do NOT want to arrive or depart Avalon.