The user interface will be massively based on technologies known as Web2.0 (such as Flex, AJAX, etc.). If a strong interactivity will be the core of this offer, you will need a fast internet connection to really enjoy it smoothly.
Adobe expects to compete with those internet-based applications released from years by Google, as well as bringing more people to know Photoshop and to invest in a standalone version of this Pro-oriented application.
