Facebook founder Mark Zuckerberg has been sending not-too-subtle signals for a long time now that the future of Facebook won’t be happening at the Facebook.com domain. The world’s largest-growing social network will take a great leap toward that eventuality this year, beginning in April.

According to a report in the Wall Street Journal, that’s when Zuckerberg plans to launch a new set of Facebook tools for Web developers – who want to make their websites off the Facebook.com domain work (and even look) more like Facebook pages on the Facebook.com domain.

That new toolkit will be called the “Open Graph API,” according to the Facebook’s Developers’ Wiki, and here’s how they’re describing it:

The Open Graph API will allow any page on the Web to have all the features of a Facebook Page – users will be able to become a Fan of the page, it will show up on that user’s profile and in search results, and that page will be able to publish stories to the stream of its fans.

Further, they go on to say,

The Open Graph API will allow any page on the Web to have all the features of a Facebook Page. Once implemented, developers can include a number of Facebook Widgets, like the Fan Box, or leverage any API, which enable the transformation of any Web page so it functions similar to a Facebook Page.

So, here’s an example. Let’s say that we here at Twittown decided that we’d like to centralize our brand identity here on the website (which is exactly what we’ve done), but tap into the viral power of Facebook at the same time. For starters, we could install Facebook’s already-existent Fan Box widget, which lets Facebook users become a fan of us on Facebook. The difference between the current implementation and Facebook’s Open Graph API is that currently, user can only become a fan of a Facebook page on the Facebook.com domain. With the new Open Graph API, they could actually become a fan of Twittown.com – the domain and website, not a Facebook page set up to represent it. That’s a significant difference.

Once they’re fans, those users would have Twittown listed as a connection on their profile – the way that on-Facebook pages are currently shown. What’s more, any content that we publish would show up in the stream of each Facebook fan, as the content from on-Facebook Pages does currently. Best of all, when those fans search on Facebook, Twittown would show up prominently in search results and in the type-aheads.

It’s pretty clear what Facebook is after here – giving users even more ways to share information. They’ve been pushing their sharing features harder and harder since 2007, when they originally launched Facebook Beacon, and especially hard since 2008, when they re-launched the failed Beacon as Facebook Connect, which has enjoyed wild popularity. Facebook’s main competitor, Twitter, however, still reigns supreme as the information-sharing platform of choice, and Facebook is working hard to close the gap.

Since the launch of Facebook Connect, loads of major brands have flocked to Facebook, driving traffic on the social network toward their branded Facebook Pages instead of toward their own domains. Making those users on-Facebook fans is a great way for brands to maintain solid touchpoints with brand advocates and potentially let Facebook users do some of the heavy lifting.

Facebook’s upcoming Open Graph API takes all of that to the next level, allowing those brands (and plenty of others who’ve been squeamish about centralizing their brand identity on a website that’s ultimately out of their control) to take those fan pages off Facebook without losing those touchpoints.

Why this huge push to get Facebook users off of the Facebook.com domain and onto other people’s website? There are two main reasons. First, Facebook’s putative Facebook Credits payment system is the forerunner for what some Facebook executives hope will become Facebook’s biggest moneymaker – the ability to position themselves as an e-commerce solution on the scale of Paypal. Second, there are plans in the eaves to launch a Facebook ad network someday, a venture which could rival even giants like Google Adsense.

Yet questions about Open Graph remain that Facebook has yet to answer. Will companies who have already created an on-Facebook page for their business be able to transfer that page, with all of its fans, back onto their own domain? How will privacy concerns and the omnipresent concerns over ownership of information play into Open Graph? Most importantly, will users flock to off-Facebook pages with the same fervor they’ve flocked to those on-Facebook? Sound off, dear readers.