Google just launched a new version of Google Calendar specifically designed for the iPhone. To check it out, visit the calendar.google.com from your iPhone browser, or download the Firefox addon that lets you update your UserAgent to make websites think you are using one.
Google Calendar for the iPhone is quite simple and is a lot easier to use than the normal mobile interface. Here is a screenshot:
Gooogle Reader for iPhone
The second unannounced application for the iPhone is Google Reader. Again, it is much sexier than the original mobile interface for the service. It has a distinct iPhone feel and I'm sure it will be used often by iPhone users. This comes after Google made a version of Google Reader for the Wii that makes good use of the Wiimote.
Google seems to be launching iPhone apps left and right -- maybe the actual search engine or Gmail will be next? To give the new iPhone interface a try, download "User Agent Switcher" for Firefox and change your user agent temporarily to this:
Mozilla/5.0 (iPhone; U; CPU like Mac OS X; en) AppleWebKit/420+ (KHTML, like Gecko) Version/3.0 Mobile/1A543a Safari/419.3