The Mozilla stand-alone browser is now called Firefox (formerly Firebird, formerly Phoenix). Both it and the Mozilla stand-alone e-mail client, Thunderbird, have new releases.
Firefox 0.8 – release notes & download choices
Thunderbird 0.5 – release notes & download choices
Note that new Firefox extensions and a new profile have to be installed for those upgrading their browser from Firebird or Mozilla.
For those using multiple e-mail addresses in Thunderbird 0.5, you can configure “smart detection” of the account you are replying from.
Other info is at http://www.mozilla.org/%5B/url%5D. (Note that the Thunderbird link above is the correct one – the one on the Mozilla.org page is incorrect.)