Microsoft has just competed its global launch of WP7 and it now appears that you can access the WP7 marketplace from your browser. This unofficial access allows you to browse apps but you can not send them to your device. Microsoft currently only lets you view the marketplace from its Zune software on the PC and WP7 devices.
Mylostblog.org has uncovered a way to parse information from WP7 marketplace so that it can be searched, the only downside is that the website is in Italian. The search engine allows you to view apps in the marketplace and gather a few bits of details about the application but currently you can only view the apps, there is no way to send them to your device.
Microsoft will most likely block this attempt in the near future as it represent unauthorized access to its marketplace. It is not known at this time if Microsoft will offer users the ability to search the marketplace from their browser or if they will continue to require them to use the Zune software package.