Reading and modifying document properties

I've been asked to do a feasibility analysis of the following requirements. We've developed an application that allows the user to set and view custom properties (the properties work like tags; e.g. a document can be tagged with "cat" and "balloon") on Office documents and PDFs. Now we need to develop something similar for SharePoint. Basically, the user needs to be able to select one or more files stored on the server and apply some property to them or view the properties that are already assigned.

Is this possible with the SharePoint APIs?

Thanks.