I was thinking, Both Microsoft and Apple are on a very tight release plan in order to be ahead of each other.
Window 7 went RTM (GM) in on 13 July, and the Windows 7 release date is 22 October. This has been known for quite some time.
It's no longer a race, 10.6 will already be out when Windows 7 officially ships.
Of course, millions of users are already running Windows 7 RC (good until March) and the RTM kits are on the torrents. MSDN (Microsoft's developer program) has the final kits and keys available to subscribers as well.
The company that releases first has most certainly got the advantage, and the company that releases second may be over stemmed by the other. So theres a real war going on here.
On the other hand, the one that releases 2nd is the "newest OS on the planet". People tend to remember the latest thing, so releasing second can be an advantage.
In another sense, Windows 7 has already "released first" through its wide-open Beta and RC program.
I think the only "war" is to have systems ready for the end-of-year shopping season. With its broad eco-system, Microsoft needs to give its partners time to optimize and "value-add" to the OS, build systems, and get them to the stores. That's why there is a three-month window between RTM and sales. (It's also a 3-month window to fix issues and have Windows Update ready for the new systems - I installed 7600 yesterday and there were already 2 updates available, although they weren't bug fixes.)
Maybe it's because of this that apple has laid all their focus on getting the actual features done and making them bug free rather than writing some 64bit drivers for older machines as this is relatively easy to realise after the initial release in the form of an update.
Other operating systems usually do core OS support first, so that those features can be tested on all machines.
I think that "Apple wants you to buy new Apples" is the more likely reason.