Frank Patrick on his Focused Performance blog has this post about Tiger and Longhorn:
Agile Tiger vs BDUF Longhorn -- This might not be a perfect analogy, but it just struck me that Apple's annual incremental delivery of operating system value (Tiger is the 5th increment of OS X) is in stark contrast to the Big Design Up Front feel I get from reading about how great Longhorn will be once (if ever) it is ready for prime time in a few years. Like I said, not a perfect analogy, since it did take Apple a while to come up with the first version of OS X, but it's close enough for jazz (and off-the-cuff blogging).