<snip>
>>  I suppose you need a different Cache directory for each active profile or
>>  the browsers will corrupt things.  How do you arrange that?
>
> we have this in the .cfg:
>
> // this file must start with // ...
> var env_user = getenv("USER");
> lockPref("browser.cache.disk.parent_directory","/tmp/.ffcache-"+env_user);

Sorry for the delay in replying, we had all sorts of stuff going on here 
for the past few days.

Anyway according to the entry at:

   http://kb.mozillazine.org/Browser.cache.disk.parent_directory

the value of browser.cache.disk.parent_directory defaults to some 'temp' 
storage on firefox >= 1.5.

Looking at about:config on an sl51 box running ffox1.5 (yes I know this is 
getting rather old), I see that for me it is currently set to:

   /tmp/MozillaFirefox-jp107/Cache/

without me needing to fix anything.  Woo hoo one fewer thing to have to 
worry about setting in any central config stuff!

As soon as our mirror of the recent ffox stuff has finished the rsync I'll 
check that the same holds true of firefox-3.0.1... as well.

  -- Jon