Google didn't share any information in the financial conference call about how many of those apps are free apps. Most likely most a few of them but if even a low percentage of the apps installed from the Market are paid, there is some money to be made by app developers. These figures from Google don't include any app installation numbers from the young Amazon Appstore. The Amazon storefront doesn't have many apps on the shelves and likely isn't selling enough to include in Android numbers.
Android tablets don't factor into these numbers in any numbers as companies are only just getting them to market. This year will see a lot of Android tablets go on sale, and it will be interesting to see how it affects these two key metrics for the platform.