It is this exact sort of communication that could really be exploited as one of the ways to offer mashups that are integrated into our workflow (as well as other inter-application communications).

You (and I) are lucky to already be enjoying it to any degree, with your example regarding Safari and Address Book - it is an advantage of having many apps from the same vendor. I’m not sure what the situation on the PC is currently?

Of course, the ones we all use are quite subtle… like for instance the embedded Google Map on website X, or the Flickr integration of website Y - that is the primary future which I see, API’s being leveraged more and more to add functionality to websites (rather than API’s being used to produce a completely new mashups). As you say, many of these API’s solve specific problems and thats where we will see them being used.

There is other value in Mashups - they let you compare wildly different data-sets, and sometimes they surprise you (Note to Yahoo: when are you going to be releasing Astronewsology? ), but sadly, unless it makes things much more useful, the web going majority probably won’t bat an eyelid.

Interesting that you brought up microformats, as I was thinking the exact same thing. I don’t see a situation where your all of the core applications on your desktop will be integrated, or mashed up togteher, but that is where I see microformats coming in. They are a bridge between applications. At the minute, I can click a button in Safari and all the hCards on a page are automagically imported into Address Book and they allow data to be defined at this semantic level, so that it can easilly be accessed. Of course the big challenge comes in getting more people to use them, but I can see microformats becoming something as big as RSS…