What would the perfect press centre / newsroom on a company website look like?

In addition to Bob's suggestions, I'd add some additional social elements  (if your company is incorporating social media). For example, if your product is very visual, consider how a Flickr stream could help reporters and bloggers add visual elements to their stories. Likewise, YouTube videos can add a beneficial dimension to a static newsroom, especially if the content is relevant to media (eg Q&A with CEO). Having links in the press room is a good start, but pulling some of that social content into the newsroom is a good next step.

A good press site should definitely *not* require a signup, because journalists hate to organize 200+ signups. Photos of management staff and facilities are very appreciated, photos of products also. It may be a bright idea to publish photos which show the usage of the products in daily life (If somebody is in need of a free photo to illustrate a story about smartphones) he may choose the pic of the nice girl, which uses YOUR smartphone. US companys may think about publishing contact informations for inquiries from abroad. Usually an US press departement does not respond at all to a question from, let's say, Germany. An I the only person who thinks that this is absolutely arrogant?

I would argue that a corporate newsroom shouldn't look much different than a consumer news site. It should have compelling content, real-time programming, integration of social media and blog content. As a journalist, customer, employee or consumer I want to know what a company is working on and thinking about when I go to the newsroom. And since search is how much of the audience will discover the content, I would optimize the templates for each individual content piece, as sites like NYTimes and WSJ do with most popular, most emailed, related articles modules. All the content should also be tagged so that audiences can find channels.

Agree with Bob and Heather. Here is an example of a good newsroom http://newsroom.orange.co.uk/#/all/1/ (but after all I'm not a journalist. It would be interesting to have professionnal journalists' POVs)

The online newsroom made sense in a day when we could readily separate the News Media from the Rest of Us. But in a day when anyone can become a publisher or a broadcaster with minimal cost and training, I could argue that your entire site is a newsroom (whether you like it or not) -- and should be designed to work that way.

I think Rusty Cawley made a good point and I can only agree with him when he says that "anyone can become a publisher or a broadcaster (...)". However, professional journalists are not yet dead and they are still the main producers of mainstream news. I think they differ from the rest of the internet users in their ways of looking up for news, analyzing facts etc... With that point in mind, I was wondering what their very own expectations are from a corporate newsroom, what kind of content they are looking for. I find most of online newsrooms to be disappointing with very poor content, and a kind of "old school" way to adress to journalists.  I really wonder how companies can adapt to a fast-changing journalism.

In addition, you might consider developing dark pages to be used during crisis communications.  For example, prestage key information on secure, hidden pages that could be moved live in the event of a crisis.  The newsroom should also be robust enough to handle traffic spikes and to take over the home page if necessary.  Communicators should be able to easily add content and edit information on the fly.