Notice I have 6 items unread in the general news folder.
Step 4: Clicking on the green icon with download all your unread feeds into the Google Gears format. Google Gears will then download them, showing you this status display.
Step 5: When it is done downloading, you will see that green icon turned grey.
Step 6: Go offline by unplugging your internet or using this little trick.
Step 7: Browse your unread feeds offline.
Notice how I now have 3 unread items in the general news folder, so I read three items offline.
Step 8: Go back online.
Step 9: Sync back up with Google Reader by clicking the green icon.
A status display will come up quickly, like in step 4.
Step 10: Google Reader will load up again.
Step 11: Continue browsing online...
Notice it removed those 3 feeds I read in online mode.
With Google Gears, Google is trying to create a standard for working with online web applications in an offline mode. This can be applied to anything. Just see the Google Gears API Developer's Guide.