I know that since 2009 Apple has been advertising the 1000 battery cycles that'll last for around 5 years under normal use for Macbooks and Macbook Pros. I don't see them advertising it in the new Macbook Air, is it the case that they have the same long lasting battery or not?
Yes - from here comes the text:
The built-in battery of your MacBook, MacBook Pro or MacBook Air is designed to deliver up to 1000 full charge and discharge cycles before it reaches 80 percent of its original capacity.
I have been bowled over at how well the internal battery chemistry holds up over time. Of course, bad batteries fail prematurely all the time and need to be swapped, but my gut feel is way more of these "go the distance" than all the older removable batteries.