iOS6 is a given. It's the only predictable thing left about Apple.
Mountain Lion will also be definitely be shown off with a release of who knows. The release will probably either be within a few weeks if the bugs are good and fixed or by the end of "summer" which always meant "September 20th" or so.
These two are given because they are the two things WWDC is about. The OS. They show off the new OS' for both their Macs and iDevices so developers can build for them. Since ML was revealed way ahead of time I'd suppose it will be released much sooner while iOS6 will most likely have the "summer" date. This has also become what Apple is now going to consider "normal". When they showed off ML in the winter they said they were switching to an iOS-like release schedule for OS X in that it will now be yearly updates with a similar release schedule of iOS which is great. As for pricing, well I want to play Devil's advocate and suggest that they may possibly switch to a FREE OS X release. After all, they're not Microsoft. They don't make their money off the OS, they make it off the hardware, and they sell a BUTTLOAD of hardware. And Apple's philosophy has always been that the hardware and software need to be made for eachother. You can't have the Mac hardware or iDevice hardware without its OS counterpart, and since they've switched to an automated update system without needing a box from a store, you can bet that they will want it to be FREE so they can get it to every machine they can as soon as possible. This is basically what Apple has been striving for since the beginning when they didn't nearly have the ability to do it. Now that it's possible, you can bet they're going to take advantage of it.
Apple TV. Well, if we're talking about a physical TV, I still think it's silly. But as for the box itself, I am hoping for an SDK finally so the Apple TV can compete with Roku. I bought my dad a Roku for Plex because I couldn't be arsed to fiddle around with Jailbreaking an Apple TV just to install a buggy Plex app. If Apple finally made the Apple TV have apps, Plex and all the others could finally put their video services on it. Plus I can totally see the games that would come out for it that utilize iOS devices. It only makes sense! I hope Apple sees this.