The Android Market Web store has been announced and is ready for release today. The system will allow users to purchase and download content from a web browser and then send the applications to their device.
To get to the web store, navigate to http://market.android.com. Here you can browse applications just as you would on an Android device.
When you click on the "Buy" button on the web page, you will be presented with the option for which device you would like to send the application to. The purchase dialog would then appear asking to confirm the purchase. Once the credit card transaction completes, the application will be sent (via cloud) to the devices that were selected.