The service will launch sometime later this year and will go against third-party gaming networks already available such as Open Feint and Ngmoco's Plus+. Clearly, Apple is serious about making the iPhone a more attractive gaming platform.
Another welcome and long-overdue addition was the unified inbox, which means users with multiple email accounts can finally read their messages from a single place rather than having to hop back and forth switching between inboxes. In addition, messages can now be organized by threads to make email conversations easier to follow, and Apple is opening up email attachments so that they can interact with third-party apps.
Jobs also demoed some new enterprise level functionality for the iPhone, including APIs for encryption, wireless distribution of apps without relying on iTunes syncing, Exchange Server 2010 support, and mobile device management for large iPhone deployments. On top of this there was the announcement of iAd, Apple's own mobile advertising service that will enable developers to monetize their software through ads delivered as mini interactive applications.
It will be a while before you get any of these features, though -- iPhone OS 4.0 will be available this summer for the iPhone 3GS and third-gen iPod touch (the iPhone 3G and second-gen iPod touch should get "most" of the features and previous versions will get none), while iPad owners will be able to upgrade in the fall. Ars Technica has posted a summarized rundown covering today's announcements, if you care to go through all of it.