It’s been about a year since Brightcove released the last upgrade to its professional online video platform with Brightcove 3. On Monday, it’s going to release Brightcove 4, and it’s a massive upgrade.

Brightcove 4 now supports a native video player on the iPhone, in Facebook, and live video streaming on the Web. It’s got Twitter integration for sharing videos, faster-loading video players, the ability to switch between Flash streaming and HTTP, adaptive streaming based on a user’s device and bandwidth, behind-the-firewall video delivery, support for most major ad servers, better analytics, and a new, cheaper, entry-level subscription service called Brightcove Express.

The biggest new feature is the iPhone player. Instead of clicking off into the Quicktime player, Brightcove uses the Quicktime APIs to render the player within an app. Developers are going to love this because they can skin the player any way they want, tie it into the same ads served through a publisher’s Brightcove player on the Web, add email and Twitter sharing, and Coverflow-style browsing.

The Facebook integration will also be popular. Brightcove 4 offers a template which allows for Facebook Connect logins with realtime comments which appear in each commenter’s Facebook stream. Brightcove videos shared on Facebook will also be playable within the stream, just like YouTube videos.

Brightcove 4 will also support live video streams for the first time. Live videos of events can be scheduled, archived, mixed with on-demand videos, and tied into the same advertising backend. If a publisher has a huge event and would rather use their own CDN, they can do that as well. Why now? “We waited until there was sufficient market demand,” says CEO Jeremy Allaire. Yet more evidence that live video on the Web may be finding its legs.

So far Brightcove is mostly used by media companies and professional video publishers who can afford to pay at least $500 a month for the service. But with this release, Brightcove is also trying to broaden its appeal with service plans which now begin at $99 a month. It’s still not a consumer platform, and probably never will be. But for professional Web video publishers and companies with video marketing budgets, the new entry point should help to expand Brightcove’s market.

I am not sure why Brightcove holds all of this good stuff back until they can package it in a new, numbered release, since it is a Web-based service, which could just as easily upgrade on a rolling basis. But doing it all at once like this does highlight all the changes to the code-base, and shows why Brightcove is considered the leading Web video platform for professional use. Brightcove boast 800 customers which use its players across 2,500 different Web sites. Collectively, they reach 135 million unique viewers per month, according to Allaire.

He won’t disclose exact revenues other than to say that it is in the “tens of millions” of dollars a year, and growing at a 50 percent annual rate. But he does say that the company, which has raised a total of $91 million in venture capital, isn’t burning any more cash. “During the first half of this year we were profitable and cash flow positive,” he says. Like everyone else, Brightcove cut back on expenses last year, and even went through layoffs of 13 percent of its workforce. The fourth quarter was the low point, but demand started picking up again at the beginning of the year, especially from branded goods companies, marketing departments, and even manufacturers looking to add video to their sites. Last quarter, Allaire hired 30 people, and currently employs 180. Next quarter he is looking to hire 30 more.