With Ubuntu 10.10, they are also hoping to establish a mechanism for "establishing and conveying a trust level for software in PPAs." In that release to come in a year, that is when Canonical will begin selling select software from the Ubuntu Software Store. Canonical is already planning as far ahead as (or at least publicly) Ubuntu 11.04 where they are hoping to have improved sharing and tracking of software within the Ubuntu Software Store and the abilities to see what software your friends may have installed and other such features.
Well, those are the plans at least. As you can see from the screenshots, right now the Ubuntu Software Store is quite basic and really does not deliver anything new to the Ubuntu package management stack besides a simplified user-interface. The main screen provides icons for different areas (Accessories, Education, Internet, Office, etc...) while there are basic search capabilities, a list view when looking at packages in a specific area or the search results, and then a basic individual package view. Obviously, there is a whole lot of work left to be done before Ubuntu 9.10 rolls around and even more is ahead for future releases. Look for the Ubuntu Software Store to appear in Ubuntu 9.10 Alpha 5.