A bit late on this one, but Nvu version 1.0 is out. Since the Mozilla organisation started making separate, stand-alone apps to complement/replace the multi-purpose Mozilla Suite (such as the Firefox browser and Thunderbird mail client), the composer (html editor) component has been lacking. Nvu is that html composer, and is, as expected, available for Mac, Linux and Windows.
Also, Firefox 1.05 is out today, Apple have released OS X 10.4.2 (best to get it through software update) and a new version of iSync, and Microsoft have issued some patches through Windows Update.