If, as now seems likely (though incredible), septuple felon Ted Stevens has in fact won his Alaska Senate race against Democrat Mark Begich, I wouldn't count on him finishing his term. The law is a bit hazy--it's been changed more than once in recent years--but if he resigns (or is expelled), a special election would be held for his seat within 90 days. What's not clear (conflicting laws were passed in 2004 by the legislature and by ballot initiative) is whether Governor Sarah Palin would appoint a temporary successor in the interim.
Regardless, though, Palin's political aspirations run through Washington, DC, not Juneau, and it seems pretty much a no-brainer for her to run for the seat if the Republican incumbent is out of the picture. (The quick turnaround of a special election would presumably give her some fairly momentous advantages--not that she'd necessarily need them.) I suspect it won't be long before Stevens starts getting a much stronger shove toward resignation, and not just from Sarah Palin.