Visto, a mobile email company that has met with some skepticism due to raising vast amounts of venture capital followed by repeated unsuccessful attempts at an IPO, has announced plans for the latest version of its mobile platform, called Visto Mobile 6. The new release takes Visto beyond email and tries to connect all your mobile social networks.

Unfortunately, I wasn’t able to demo the product, but from the slides that Chief Marketing Officer Doug Brackbill showed me, the product looks very cool. It’s not a mobile social network per se (like Loopt, for example), but rather a service that keeps users updated on all of their contacts’ social activity. Instead of logging into each social networking service, you can get a summary from Visto Mobile 6 on all your contacts and their new activity on sites like Facebook, MySpace, Flickr, Twitter and so on. Then you can log into each service if you want to know more.

The Visto Mobile 6 social networking tool is also a good launching point for reaching out through email, instant messaging, text messaging or plain old phone call. (See example below.) The new version also includes a network address book called the Visto Mobile iPortal, and new features for email, like support for Microsoft Exchange.

Today’s announcement is promising, but the other question is when users will actually see the product. Since Redwood City, Calif.-based Visto works through the mobile carriers, Brackbill says he can’t offer a concrete timetable, except that he hopes to have Visto Mobile 6 working on at least one carrier by the end of the year.

And there are those who aren’t inclined to take Visto seriously anyway — after all, it has raised more than $350 million in venture capital without an exit and earned a reputation for being rather litigious, leading my editor Matt Marshall to call it “Silicon Valley’s most controversial company.” Still, if Visto is seeing the kind of growth that Brackbill hints at, and if the new service lives up to its potential, skeptics may change their minds soon enough.