The bottom line is, you can't just ignore the need because the largest room in your company seats only 80 people. You can hardly rent a hall every week. When you communicate a common message to all interested constituencies, you want it to be pretty even. In a large project, when people don't have an enormous amount of time, you need to condense the news down to its essence for the majority of the team. Consider creating a weekly videotape that operates the same way as CNN's Headline News.
Every large effort has a number of specialists.
Usually, the more technical they are, the more they lack communication skills. I would dedicate people to work full time at understanding how to communicate and making sure that it actually happens throughout the project. Communicating up the ladder, to senior executives, is a little different. So there's a different aspect to the communication flow. They're much less interested in telling the higher-ups how the system is going to work and getting input on what the system will do than in making sure that the executives have enough information to lead effectively.