okay, not entirely true. i recently got a comment on how sharepoint might not make it in a company because one of the features, a rich editor for html that is used in rich edit areas, wiki, blog, etc., does not support firefox as a browser. basically you can still edit, but you don't get the WYSIWYG environment.
well, there are a couple of options. first, the hack (i haven't even tried this to be honest so i shouldn't even be announcing it :-)). in web.config (since sharepoint 2007 is an asp.net app) you can add <browserCaps> elements to the configuration section to "help" asp.net realize you have a modern browser. slingfive.com provides a suggested file you can download and add in your web.config (please back up any web.config before you modify and test in a non-production environment).
or...the better option. our friends at telerik are providing and editor alternative for licensed sharepoint users. you can read their press release to learn about the deal and you can sign up for the current beta. they are providing an installation experience that is one-click so you don't have to mess with settings, etc. the support for this would come from telerik. this is great of them to do and they've done it in the past with commerce server (as pointed out in their press release).