Okay, clarifying things a bit here, as it would be confusing to a newbie:
yup. 3 times. on any apple product.
yup, that is the rule i have seen used.
These answers are simply incorrect.
As was stated by both KorDorSean and caribiner23 and others:
There's no hard and fast rule within Apple as to when a machine will be replaced. If there's a serious problem that gets escalated to the right level the computer will be replaced. I speak from first-hand experience.
there is no "rule" that states that if you have three issues with your mac they will replace it.. even if its the same issue three times there is no 3 strike rule..
This is the correct answer. There is
no steadfast rule that gives any specific number of times that Apple has to attempt to repair something before they give a full replacement.
That decision lays directly on the supervisor's shoulders. Each store may set a "house rule", but that does not make it the company-wide rule. Also, no phone rep is going to seriously be able to give that sort of guarantee... at least not before the situation even happens, if it ever would happen.
Do NOT go into this thinking that you are automatically going to get a brand new replacement if you have to send your computer in for service three times. Not even three times for the same issue, even if those three times are not in succession.
The decision for replacement will be made if and when the tech supervisor has deemed it as such.