Seems most aluminum frames come with a 5 year warranty, steel typically gets lifetime.. not sure about carbon but im sure its 5 years too.

I personally don't believe the whole aluminum shelf life or "good for XX miles" thing, look at all the cannondales and treks still kicking around since the late 80s/early 90s, not to mention all the aluminum components built since the 1960s and in some cases older.