It would be very difficult to include support for any of the Macs Apple produced before relatively recently because of how AirDrop works. It uses an ad hoc wireless network to look for the Macs in close physical proximity and then transfers the file over. The catch is that it does this without ever dropping the connection to the wireless network the Mac is using for the Internet. This is only possible with a wireless card that supports being connected to two wireless networks at the same time. None of the Macs before late 2008 had such a wireless card. It's the same reason older Macs can't take advantage of a dual-band wireless N router in the same way more recent models can. So Apple could enable AirDrop for older Macs, but it would only be available when not already connected to a WiFi network. Yes, this might actually make a lot of sense in the context of a desktop connected by ethernet, but I'm guessing Apple didn't want to deal with millions of user complaints about AirDrop's availability being inconsistent since a lot of people use their iMacs and Mac minis on wireless networks.
On MC, all I have to say on power use of it is that everything that can be done in MC, I can do with Snow Leopard's Spaces or Exposé in at least one less click/key press/swipe... and there are a number of features that simply can't be replicated. Below is the list of things Mission Control can't do that Spaces/Exposé accomplished quite well:
- Ability to tell which Space you're using by looking at the the menubar
- Ability to align Spaces in a grid and switch between them non-linearly (going to the next row)
- Ability to see all your spaces in a view large enough to actually see the windows easily
- Ability to "Exposé" all your windows in all your spaces at once when in "Spaces" view (now Mission Control view)
- Ability to manually rearrange the order of Spaces
- Ability to freely drag windows between Spaces when in "Spaces" view (now Mission Control view)*
- Using Ctrl+ [Space number] to get to a specific space **
- Ability to fullscreen something on a second display without killing your ability to use other displays entirely (this is a direct consequence of the new fullscreen mode creating a new Space)
- Ability to see the second monitor when viewing/organizing your Spaces***
- Having the windows in "Exposé" (now Mission Control) view each labelled with their titles
- Ability to see all your windows in full on the "Exposé" (now Mission Control) screen; currently, any application with more than one window open has most of its contents obscured****
- Ability to see minimized windows****
*This can be worked around if you're willing to bring a window of interest to the front every time you want to move a space. Extra clicks/swipes.
**This can be done for some of the spaces in Lion, but it does not work for any space that was created by a fullscreen application.
***You can run Mission Control on the second monitor to see this separately from the main one. This is highly disorganized and not all that useful, though.
****This can be worked around if you use the Application-specific Exposé, again requiring extra clicks/swipes unless you only have minimized windows in one app.
Needless to say, Mission Control has a long way to go before I accept it as a real power user tool. The complicating of multi-monitor workflows is an especially egregious offense since this used to be an area where OS X's way of doing things far surpassed Windows', but I at least have some degree of confidence Apple will fix that. I'm mainly worried that Apple's approach with OS X may be taking a direction similar to what they did when they crippled Final Cut Pro for the sake of making it more accessible to casual users. I hope that isn't the case and am willing to give them the benefit of the doubt, but I'm certainly going to be paying a lot of attention to what Apple does with Mountain Lion.