When I started working with the development team abroad, they suggested we use Basecamp to stay in synch. I had heard of the company 37 Signals but had never used any of their products so I was really blown away once we got the project up an running. The service includes a message board, shared task calendar, To Do List, a writeboard, and file sharing service and an easily to manage contacts list.
The team put all of our milestones into the system so now I can go to Basecamp, review the list of upcoming milestones and leave files and comments that I think are useful for the team. Once you upload or insert a new comment you have the option of notifying specific group members which is great because it avoids spamming those people who are not relevant to the update.
I think this software is really a brilliant way to manage a geographically separated group of people where transparency can obviously be difficult and it is hard to get clarity around what each person is doing. I seriously recommend Basecamp for anyone collaborating on not just software development, but anything that could require getting a group of people on to the same page.