Gmail

Integration is moving beyond being a buzzword, and is actually beginning to work. RSS is probably the big thing here, as it gives the most flexible way to aggregate information from diverse sources. But there are lots of other encouraging examples.
The first thing is that I'm now using MacJournal to post this blog entry. I had always thought of MacJournal as being a tool for taking notes on my own computer, but this integration is such a natural thing to do, as blogs are often thought of as journals.
Another example is that VoodooPad now features integration with Address Book. Write a name in VP and it becomes a link to the corresponding entry in Address Book. I had always thought that this kind of integration would have to wait for Tiger at the earliest, but it's here now. VoodooPad has long featured integration with the Finder, in that dragging an application, folder or file into a VP page creates a link to it, meaning that it can be made into a kind of project center, like Entourage but much more flexible and less resource-intensive (and very cheap). It also allows you to convert a VP document into an online wiki.