There certainly are a number of changes in Windows 7 that vaguely bring the Mac OS X dock to mind - jump lists, for instance, resemble the right-click menu on dock items, and the removal of text labels and increase in icon size make the taskbar look like the dock (you can change to small icons and text labels if you so desire). However, that doesn't mean it also behaves like a dock. If it looks like a duck, walks like a duck, and talks like a duck, it's probably a duck, yes - but this one only looks like a duck; it doesn't walk or talk like one.
The taskbar in Windows 7 is still the taskbar that you know from Windows 95, 98, 200, XP, and Vista. Each window (except some dialogs - sadly) gets its entry into the Windows 7 taskbar, just like in previous releases. This is different from the dock paradigm in Mac OS X, where each application gets an entry in the dock. This may seem like a minor difference, but in fact, it's one of the defining differences between the approach to documents and applications between Windows and Mac OS X. Consequently, it's also one of the most common initial problems Windows users face when switching to Mac OS X. Close all Word taskbar entries in Windows, and the application Word is no longer running. Close all Word windows in Mac OS X, and Word will still be running.
One area where the taskbar really makes a step towards the dock is when it comes to allowing applications to 'live' in the taskbar, effectively integrating the quick launch area into the taskbar. The result is dock-like behaviour: the taskbar now not only shows open windows, but also application launchers. Icons on the taskbar become "representations" of applications, central points where you can manage the application's windows, its functions, and its state.
I think it makes sense. Most Windows applications adhere to the single document interface concept these days, meaning that each window of an application appears to be a separate instance of said application. In that context, it doesn't really make sense to differentiate between an application "launcher" and its taskbar entries.
After having used the new taskbar myself, I hardly call it form over function. The changes made make a lot of sense when you use them, and it took me little to no time to adapt to them. The various changes are all based on solid data and research, and this shows when you first use it. These changes aren't "form", they are strictly "function". It reminds me a lot of Expose, one of the most brilliant interface concepts of recent times. It looked like pointless eye-candy at first, but five minutes after using Expose, it just makes so much sense, and you realise that while Expose looked like mere "form", it was actually strictly "function".
If the new taskbar brings Windows closer to Mac OS X - who cares? If it happens to work better, why shun it; just because it resembles what your competitor has to offer? In Dutch, we have a saying: "beter goed gejat, dan slecht bedacht". This translates roughly into "it's better to steal something good, than to come up with something bad". The computer industry consists of a huge group of people who continuously steal each other's ideas - in fact, every industry is made up of thieves. It's just the way mankind works: we come up with ideas, and they spread. Deal with it.