Depends what you mean by 'save the test'.
If you mean 'win', then probably not. Too much ground to make up, not enough time.
If you mean 'play for a draw', then f*ck yeah they can save it! The poms need another 15 wickets remember! Plus they're going to have to bat again themselves (can't see them enforcing the follow-on even if Australia doesn't make it past the mark - although they are bloody close right now...)
Who gets picked for Perth? All depends on Watson. If he is fit and they still want to pick him, then that would be the only change. Assuming McGrath etc pull up fine from this Test - but there is a bit of a break before the WACA Test, so he should be fine.
Clarke is batting nicely now, and hasn't done anything to deserve to be dropped. Hayden and Martyn have failed in all their innings this series (Hayden 3 times, Marto twice) but again neither is likely to be dropped.
I'd stick with the same team personally, but they're more likely to drop Clarke than anyone else - which sucks, because he's looking fairly good in the middle right now.