Binabik: From what i can gather, most of the tweaks that Fasterfox used to make to about:config are built into FF 3.0, though i do not know if they all are. You can still make changes yourself to config, but its not wise to unless you know what you are changing
I will try to find out more about Fasterfox though, i know that most of the Add-ons that are not yet compatible with FF 3.0 is because the people that wrote them seem to have vanished lol
I do not know if the writers of Fasterfox are working on a update or new version, BUT the reason the old version does not work is very simple.
The .rdf file that is part of the .xpi file that is the actual extension contains the lowest and highest versions of Firefox that the particular extension has been tested on and will run in. In other words the present Fasterfox download will not run in anything past Firefox 2.*.* unless you yourself change the .rdf file.