The FIA has published its proposed 2008 Formula 1 Technical Regulations, with suggested changes to the Sporting Regulations thrown in for good measure. An overview of the Tech Regs is here, and the full version is here (pdf file). A document highlighting the changes between the 2006 and 2008 regulations is here (pdf file).
The FIA says that it's required to publish the 2008 regulations before the end of 2005, which explains the timing of the announcement.
The most interesting thing about the entire announcement is the FIA's overall objective with the rules changes: cutting costs. In FIA President Max Mosley's words, "The real argument in Formula One is not about sports governance or even about how much money FOM gives the teams. It's all about costs."
However, trying to legislate lower budgets by fiddling with technical regulations would seem to be a losing game. Manufacturers with money to invest in F1 (whether it's a sensible investment or not is beside the point) will find a way to spend it. If you restrict track testing, big teams invest in more sophisticated simulation, for example. And so it goes. As long as manufacturers and sponsors see benefits to being involved in Formula 1, or any other racing series, they will be prepared to put up the budgets that match the perceived benefit.