Hello dpisano, No, unfortunately ACT! E-Marketing cannot be implemented in the web database. However, you can still sign into your Swiftpage account directly and use your templates. It just won't be integrated with the ACT! database. You would need to install ACT! on your machine for full integration.
Note: Effective 6/1/13, Sage no longers provides support for the Act! software. This is now provided by Swiftpage.