This is a pretty controversial subject, but I think the consensus is that you won't be able to taste any off flavors and that aluminum is fine. I have a SS keggle but I also have a 16 qt aluminum pot and I'd have no hesitation using it for sparge water or whatever.
I brewed with a friend of mine who uses turkey fryers w/ aluminum pots a few weeks ago and the beer came out fantastic...
Just make sure you don't use your aluminum pot for anything very acidic like tomato sauce or a vinegar-based dish.
Bottle conditioning: Robust Porter
Drinking: Saison Dupont clone, tripel
Coming soon: Columbus APA, Rich Red ale