I have never been a fan of Adobe Systems' Portable Document Format (PDF) or of Acrobat, Adobe's family of applications for creating and reading PDF files. Adobe introduced the format back in 1993, when the World Wide Web was still an obscure physics project and "electronic publishing" meant designing print documents on a computer screen. At the time, Adobe was known mainly as a proprietor of digital fonts and image-editing software used by many publishing professionals to produce documents intended for printing. It invented PDF to preserve the design of such documents, regardless of which computer was used to create, view, or print them.

Fair enough. PDF is indeed useful when it's important to capture the look and feel of a print document; in fact, I'm a loyal customer of Octavo, a company founded by Adobe's former CEO John Warnock that scans rare books and publishes them in stunning, high-resolution PDF form. But working with print documents is no longer personal computing's killer app. The Web is. And compared with most Web pages, PDFs feel sadly static and fossilized.

But now something has happened to make me take a fresh look at PDF and Acrobat. In a nutshell: Adobe Systems has discovered social computing.

Over the past few years, the Web has grown from a one-to-many medium, in which authors essentially published documents for the benefit of an unseen audience, into a tool for advanced one-to-one and group communication. Technologies such as social networking, media sharing, voice calling, and video conferencing have transformed the Internet into a locus for all things social, as exemplified by sites like MySpace, Flickr, Skype, Meetup, Upcoming.org, YouTube, and Dodgeball (see "Social Machines," August 2005). With the Acrobat 8 suite, released in November, Adobe has moved decisively into the social-computing era.

I've spent the past few days testing Acrobat 8 and an associated Web service, Acrobat Connect. I'm pleasantly surprised by the number of new features Adobe has provided to help people work together on documents over the Internet--even if those documents aren't PDFs. When combined, Acrobat 8 and Acrobat Connect form a powerful (and potentially cheaper) alternative to established collaboration and presentation systems such as WebEx and Microsoft's Live Meeting and Office Groove 2007. They also show how Adobe is beginning to benefit from its 2005 acquisition of Macromedia, the company that founded the interactive-multimedia industry.

Veteran Acrobat users needn't worry that they'll lose anything. Acrobat 8 includes all of the core functions of Acrobat 7, including the ability to create, review, search, encrypt, and export PDF documents, and to convert other kinds of documents, such as e-mails, Web pages, and Word files, into PDFs. (I tested Acrobat 8 Professional, which retails at $449. Acrobat 8 Standard, at $299, leaves out a few specialized features, such as the ability to work with CAD documents and create fillable PDF forms. Adobe Reader 8.0, the latest version of the company's stripped-down PDF viewer, is still a free download.)

It's the new collaboration features, however, that have me rethinking my negative attitude toward Acrobat and PDF. The features change PDF files--which I'd always seen as the electronic equivalent of museum cases, preserving sacred, untouchable text--into living documents that any number of people can alter, either separately or in concert.

For instance, Acrobat 8 allows users to create blank PDFs and add text by typing, just the way one would with a new Word file. That's a major shift in itself; it means PDF can be a document's "native" format, not just a way to package material created using other applications.