During the “Feed Me: Bite Size Info for a Hungry Internet” panel today at SXSW (moderated by VentureBeat’s own Eric Eldon) all the participants agreed that social streams of data are going to be an integral part of the web going forward. David Sacks, the chief executive of Yammer, went farther, calling these streams “email 2.0.” No one seemed to disagree.

With Facebook’s new redesign now fully in place and focusing on real-time updates in your feed, the concept of social activity streams is moving into the mainstream. And while Facebook previously helped bring the idea of the news feed itself to the mainstream, this next iteration which includes live updates, comments and “likes,” was pioneered by others. But everyone on the panel today, which included representatives from FriendFeed, Microsoft, Yammer and Facebook, seemed to agree that the future of this space was making this data accessible no matter which service you are using.

FriendFeed co-founder Paul Buchheit likened it to the old days of AOL (the dial up, closed system variety), when you could only send email to other AOL users. Eventually, he noted, AOL was forced to open up to these messages to the rest of the Internet. He believes that status updates will eventually become a federated medium as well. And perhaps it’s no accident that Buchheit started one of the services which is already helping to spread this social data around the web (it both pulls in and posts back to Twitter, for example) — when he was still at Google, he helped create Gmail. So maybe the social stream really is the next email.

A lot of these services even look a lot like email. The central focus is on a stream of messages, with the left hand side devoted to filters, which are more or less like folders, as Sacks pointed out. One company, Microsoft, is even using its email service, Hotmail, as the foundation for its social stream. Others, like Yahoo, are starting to do this as well.

During the question and answer session, David Karp, the co-founder of Tumblr, who was in the audience, asked why any of these services really matter — why not just use a standard like RSS to syndicate this data everywhere, he wondered? Dare Obasanjo of Microsoft pointed out that the reason people need services for the social stream is that while something like RSS may be fine for the tech savvy crowd, mothers or grandmothers would take one look at it and not understand what is going on. Seeing everything in a stream on Facebook though, and having a simple publishing tool that makes it clear how you insert pictures and other elements, is the key for the mainstream.

Ari Steinberg, an engineering manager at Facebook, more succinctly noted that while the concept of RSS is sound, the interface has failed. Each of the companies on this panel are attempting to put the right interface on this new movement.

But not everyone agreed on all points. Sacks made it clear that he felt that with Facebook now fully in the social stream arena, it stands a good chance of being the clear-cut winner in terms of users. That doesn’t bode well for other services out there, like FriendFeed. Sacks believes Yammer can excel however because it’s focused on streams for businesses, and he doesn’t believe that users want to mix personal streams with business ones. Of course, he didn’t bring up to possibility of a large business social network like LinkedIn getting into the space.

While these panelists were a solid core of the stream movement, there was one glaring absence: Twitter. One audience member noted as much, to which everyone laughed. (SXSW invited Twitter to participate in the panel, but it turned down the opportunity.)

Twitter, the current media darling of the lifestream movement, may have not been there, but it was on everyone’s mind. In my notes on the panel, I counted 13 different mentions of Twitter by the panelists. Steinberg downplayed Twitter’s importance a bit — notable because Facebook tried to buy Twitter in November of last year, and its new update emphasizes some similar functionality. Steinberg noted that Twitter was pretty simple, but Facebook offered a lot more functionality.

And, the way it handles relationships is very different. On Twitter anyone can follow anyone else (assuming they have an open stream). On Facebook, you need to confirm users are your friends — though, that is changing a bit with its new Pages.

Towards the end of the panel, the issue came up of people being wary of Facebook taking over the social streaming space because of its traditionally closed model when it come to data. Steinberg reiterated the more recent company line that its committed to allowing users to share data both inside and out of Facebook, but that user privacy remains a bit of a road block.

If the stream really is going to be the new email, that road block will need to be removed. Or, as Buchheit mentioned, Facebook may one day suffer the same fate as the old AOL.