ustreampageFacebook’s new Live Stream Box is a cut-and-paste HTML widget that can be added to a website to let Facebook users chat alongside a live event. Updates to the stream post quickly and then wash off the screen, to maximize the live-event feel.

In the example shown below, Mashable founder and poster boy Pete Cashmore has set up a Live Stream Box next to a video window.

cashmoreAt the same time, Facebook and Ustream have integrated Ustream’s live video technology so that it will play within a Facebook page. But Ustream won’t initially be available on regular people’s pages. The initial collaboration between Ustream and Facebook will be limited to pages that tout brands or entertainment artists, such as the Jonas Brothers shown here.

Why won’t Ustream be available for everyone on Facebook? Because Ustream can’t support that many sessions, and because Ustream custom-builds the player page. There’ll be a submission process for people and companies who want to be able to stream live. Ustream will choose those it wants to work with. There are two flavors of custom-built Ustream: An ad-free version that requires a development fee, and an ad-supported version. Ustreams sample page for the Jonas Brothers, above, calls out the headers (the area labeled a) and banners (labeled b) that can be customized.