As much as it may seem as if the entire license will be changed, it is important to realise that it is not Mozilla's goal to change the scope of the license; the focus is on the wording. "We will modernize, maintain, and simplify the license," Mozilla writes in the accompanying FAQ, "We may make some policy changes (such as becoming compatible with Apache or adjusting our patent license grant) but we do not plan to make major changes, like switching licenses or altering the scope of our copyleft requirements."
Despite not making any changes to the license's scope, the version number will probably still be bumped to 2.0. "There will be a lot of usability improvements to the license, whether or not we make any policy changes," they explain, "As a result, we'll probably end up calling it '2.0' - though that decision has not yet been made."
As you may expect, the Mozilla Foundation is inviting everyone to aid in the process, asking for input on the current version of the license. You may also join the mpl-update mailing list to keep closer tabs on the process.
Mozilla aims to have the process completed by October or November 2010.