Michael Vogt from Ubuntu development team showed off a really cool feature on his blog today that allows you to test drive an application from software center without actually installing it.
To enable this feature in Ubuntu 11.04 you need to install qtnx package from software center that will let you establish a remote connection to a server using NX protocol and Weblive API. This feature is already enabled in Edubuntu 11.04. However as of now, not all applications are supported.
After installing qtnx go to an application in software center and you will find a new button below secreenshot of the application. Click on it and select an option:
It will take a moment depending on your connection. Once connected, you can try out the application in a new window.