Okay so I was playing around with a few things today with Mountain Lion and there were a few glaring holes that I've been noticing lately that you'd think Apple would have made "Just Work."
Keynote through Apple TV: I've looked around online and I haven't seen anything showing how to do this, and I thought I must have just been missing something obvious. It appears that the Apple TV doesn't allow a way to work as a second display for Keynote on either the iPad or the Mac. Given Apple's big hubbub about AirPlay Mirroring you'd think that this would have been a no brainer!
Back to My Mac for iPhone: I've noticed Back to My Mac is still a feature of iCloud, but with iDisk dead there's no easy way to access certain types of files that iOS devices can open unless there's a corresponding app for it.
The first one is just dumb, the second one is genuinely frustrating. My sister is looking into getting an iPad for a law firm she's looking to start up. She wants her assistant to be able to drag and drop files into a location where she can then view them on the iPad. Makes sense right? But these aren't going to be Pages, Numbers and Keynote files. These are mostly going to be scanned hand written images or PDF files. And looking around on the app store I see one app that looks like it might work (Air Doc) but the UI looks confusing. I told her that dropbox was probably the best choice but she found that their privacy policy allows employees to read file names so it won't work for her. (I suggested giving all clients nick names and she told me that wouldn't work.) At this point I've actually recommended she look into Microsoft's Skydrive.