Wi-Fi calling: We've all been there: You need to make a phone call, but your cellular-network signal is pretty weak. With iOS 8, if you have a strong Wi-Fi connection--and your carrier supports it--you can make calls and send text messages over the Internet. T-Mobile has already said that it will be onboard when iOS 8 launches this fall; we expect we'll hear more from the other carriers in the not-too-distant future.
Rich-text editing in Notes: The built-in Notes app in iOS has never been particularly complicated, but in iOS 8 it finally gets support for rich text. So if you've been dying to bold, italicize, or underline your important personal jottings, iOS 8 is the update for you.
Travel-time notifications: In OS X Mavericks, Calendar let users specify how much time it would take for them to get to an appointment, so that the app could properly notify you when it was time to leave. (In some cases, Calendar could even do that automatically, if it knew where you were and where you had to go.) It looks like that same functionality has come to Calendar in iOS 8--no surprise, given that the Today view in Notification Center could already often provide that information.
There are a host of new accessibility features in iOS 8. VoiceOver can now use the much more natural Alex voice that OS X has long sported; there's multi-device support for Made for iPhone hearing aids; improved zoom; a "speak screen" action; and support for a Braille keyboard with direct 6-dot Braille input.
The Guided Access feature introduced in iOS 6 gets a few new additions as well. For example, you can now authenticate via Touch ID to exit the Guided Access mode, as well as impose time limits and a countdown timer.
To be determined
As always, there are a handful of things on the slide that weren't self-explanatory. For example, there was a reference to a Tips app (which we assume involves tips for using your device, and not simply calculating your gratuity at a restaurant), the promise of flyover city tours (see Paris without ever leaving the comfort of your home?), and place cards in other apps (presumably so you know where to sit the next time you visit Downton Abbey). For these, we may have to wait until iOS 8 debuts to get the full details.