A good roundup by The Verge:

…this was a software-focused show. OS X 10.10 Yosemite and iOS 8 bring the desktop and mobile device closer together than they’ve ever been before, and a host of new developer tools should enable the creation of some powerful new apps. That includes a new programming language, Swift, which Apple hopes will replace Objective-C over time.

My favourite thing in the moment, as I was watching the keynote was the announcement of the new predictive keyboard and support for third-party keyboards like Swype, Swiftkey and Fleksy. I'm probably going to find several other things they announced to be much more significant in the long run, but I've been waiting for third-party keyboards for a long time, so I was pretty pumped.

Apple’s new predictive keyboard provides you with smarter auto-complete suggestions, giving you a choice of several words and phrases based on the context of the text you or your contacts just wrote, as well as on your full typing history. The new feature, called QuickType, can even answer questions for you. Apple says it does this by "learning" your typing habits and does so while respecting your privacy. Finally bowing to years of requests, Apple now lets you install and use third-party keyboards by default across your iOS devices.

I think this is a big step for Apple. First we can change our default keyboard, then maybe one day we can change our default browser of mail client.