Facebook has just started sending out invitations to f8, its semi-regular developer conference during which it typically rolls out its most important features.

This year’s event will take place on September 22 in San Francisco and will take place at the San Francisco Design Center. The event’s official (and very nifty) splash page is right here.

A post on Facebook’s developer blog says that we can expect there to be “some exciting product announcements that enable a new class of social apps”, as well as Q&A and sessions on building social apps.

The last f8, which took place in April 2010, was absolutely huge: it featured the launch of Facebook’s Open Graph API and the now-ubiquitous Like button, as well as several of Facebook’s social widgets.

It also saw the launch of Instant Personalization — a bold feature that allowed select third party sites to access some of your Facebook data as soon as you landed on them (the opt-out nature of the feature drew plenty of criticism).

We expect to see similarly major announcements at this event.

This is the fourth f8 (Facebook had its first in 2007, but didn’t have one at all in 2009). Facebook had previously confirmed that it would be holding an f8 this year, but hadn’t previously announced the date.

Here’s the description from the invite:

This all day event with Facebook engineers and product teams will feature keynotes and session tracks that highlight our new tools along with best practices for developers and partners building the next generation of social experiences.

Crunchbase

• FACEBOOK

Company: Facebook

Website: facebook.com

Launch Date: February 1, 2004

Funding: $2.34B

Facebook is the world’s largest social network, with over 500 million users. Facebook was founded by Mark Zuckerberg in February 2004, initially as an exclusive network for Harvard students. It was a huge hit: in 2 weeks, half of the schools in the Boston area began demanding a Facebook network. Zuckerberg immediately recruited his friends Dustin Moskovitz and Chris Hughes to help build Facebook, and within four months, Facebook added 30 more college networks. The original idea for the term...

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