You should see red badges on the App Store icon in the Dock if there are updates available whether or not the App Store is open.
I'm all the time signed in with my Apple ID, but i have to open the app store application and have to klick on the update button to see available updates. Is this correct?
BTW, better to logout of the App Store when you're not downloading apps or updating or just perusing the apps.
thanks for your reply. Is there anything i could do to solve this problem? I reinstalled the 10.7.3 Combo Update, signed in and out with my Apple ID a few times and did a few reloads of the site.
When i hit the updates button in App Store it shows me the badge in the dock for one update. I close the app - the badge stays there. I wait one minute and start the App Store again - the badge disappear. I hit the updates button, the badge appears ... and so on.
There appears to be a bug in the App Store as far as the badges for updates go. You can try deleting the cache associated with the App Store.
Quit the App Store.
Go to ~/Library/Caches/com.apple.appstore/Cache.db
For Lion v10.7x: To find the Home folder in OS X Lion, open the Finder, hold the Option key, and choose Go > Library
Move the Cache.db file to the Trash.
Relaunch the App Store.
The other people replying above are incorrect.
Unfortunately, the Mac App Store will NEVER automatically update its icon in the dock with a red badge for pending app updates. You are ALWAYS forced to manually launch the Mac App Store to see if updates are available. It's really quite ridiculous & silly & cumbersome, and it prevents people from running the latest versions of their apps. Apple really needs to change this behavior.
The ONLY time that the badge will update on its own is if Apple has released an OS X software update that they consider "important". Then, the badge will update on its own.
Other than that, you're sadly on your own.