The web is resonating with speculation today as to what’s going to be unveiled by Facebook at an event Monday. Invites went out to various news outlets today, stylized to look like an express mail letter, including large messaging iconography. The prevailing thought is that the announced “Project Titan” could become the release of personal “@facebook.com” addresses for users—a move which would put them squarely across the battlefield from Google with their Gmail product.

Facebook does have an inborn messaging system for contacts to send notes to each other, except that it’s clunky and difficult to use. Most of the Facebook experience is wrapped around connecting with users publicly, with almost every interface with another user displaying a Like button, share button, or a field to type into. Getting into the messaging system takes several clicks, and eventually pops up an overlay box for typing the message. Also right now, users must visit Facebook in order to engage in private messaging.

A Facebook e-mail product would permit its contacts to escape from the confines of its pages and actually use it as a communication service—and, amid rumor that it might connect with Microsoft’s online Office tools.

The titanic clash that could follow between Google Mail and Facebook Titan would also be a collision of paradigms—one that we see often across the technology sphere: open vs closed. Google runs on a platform of openness, allowing great and unfettered access to its Gmail service to its users, permits them to download their entire archives, connect with various 3^rd party services, and enables users to easily use it as for storage and forwarding. Recently Google began to enforce a reciprocity policy with other online social networks which quickly caused the search giant to lock horns with Facebook who currently run on a lock-in model. Where Google will happily import an export user contacts and data; Facebook runs purely on the import model, you can check out, but you can never leave.

As a social networking giant, Facebook is well poised to move out into the wild, wild west of e-mail, to unshackle its users from using its interface and its webpage to communicate. Although this will take a bit of a shift in thinking for them because it will mean user activity will be out of reach for advertisers and immediate access to the Like button—slightly out of view of the social network. A vast, strange space that will have Facebook groping in the dark.

They’ve come a long way to dominate the social market, but the e-mail game is entirely a different scheme and Gmail appears to have that solidly buttoned up. To the extent that Google’s product looks very tempting to small businesses and some corporations with other powerful e-mail products on the market like Microsoft’s Exchange webmail. While Facebook may make it to the field with Project Titan—if the announcement turns out to be an e-mail product after all—it will still have a great deal to prove in usability and interoperability before anyone takes them seriously as an e-mail client with the other veteran titans already grappling for superiority.