Here's the simple process to start using these Gadgets right away. (Note: this assumes you've already got a Webmaster Tools account and have verified at least one site.)
1. Visit Webmaster Tools and select any site that you've validated from the dashboard. 2. Click on the Tools section. 3. Click on Gadgets sub-section. 4. Click on the big "Add an iGoogle Webmaster Tools homepage" button. 5. Click the "Add to Google" button on the following confirm page to add the new tab to iGoogle. 6. Now you're in iGoogle, where you should see your new Google Webmaster Tools tab with a number of Gadgets. Enjoy!