Once you click the "Add to Chrome" button you should see a pop-up window like the one above asking whether you want to enable the Chrome App Launcher. Click "Get the launcher" to install it, and a 9-square grid should appear in your taskbar. Like any good Windows app, installing App Launcher will also add a launch icon to your desktop.
After the launcher is installed, you will be asked to continue installing Text Drive for Chrome as you normally would by clicking "Add" and downloading the CRX file.
Once you've got the app launcher, all your Chrome apps will be available from your taskbar and will no longer appear in the browser when you open an empty tab. Click the Chrome App Launcher and a pop-up window will show all your Chrome apps. The app launcher can display 16 apps at once, and you will be able to scroll to a second page similar to the way you would using an empty tab in Chrome. Any Web apps you open show up as a new tab in your current Chrome session while packaged apps appear in their own window.
Adding the Chrome App Launcher to traditional desktop PCs should be a helpful addition for hardcore Chrome users who need easy access to their Web apps. Chrome's launcher also adds a little bit of that Chrome OS feel to other operating systems, which may be Google's real goal. I can't help wondering whether Google plans on other Chrome OS features to its Windows and Mac browsers in the hopes of convincing more desktop-bound users to give Google's cloud-based notebooks a try.