GMDesk is the kind of application only Google fans would install. In any case, if you use Google apps on a daily basis, you may find it useful too.
With GMDesk you gain automatic access from your desktop to several different Google tools, including Mail, Calendar, Docs, Maps, Reader and Picasa web albums. The big advantage of using GMDesk is that you don't have to open your web browser, load the website of each one of those services, login with your username and password and then wait for it to load. GMDesk is not faster than your browser, but it makes the whole process just easier.
GMDesk is based on Adobe AIR and has no settings menu except for the possibility to choose which Google service you want to load first on launching the program. Like I said, GMDesk may be interesting for Google fans, but I wonder if it's really necessary, as it doesn't really add anything new to the Google apps we all know.
If you're hooked on Google apps, GMDesk is made for you: an app launcher that enables you to access Google tools right from your desktop.