There is an "make Firefox the default" app posted as an attachment to the bug https://bugzilla.mozilla.org/show_bug.cgi?id=499904 -- this didn't ship with the product, but can be installed separately to intercept requests for the browser and direct them to Firefox.

Also, try this Maemo application: http://talk.maemo.org/showthread.php?t=38273

The firefox for n900 isn't work better,,,, always fail download the pages from sites, and this is the unsolved problem that i had since i m using my n900,, just 14 months ago.

I m suggest to firefox, so as you, to taken away your firefox from our n900, because it is a spammer at our mobile.

better to use n900 without your firefox. i m very disappointed when your firefox@n900 is slowly browsing than my nokia n5800.

AND TODAY.............. I SAY.... FIREFOX WEBBROWSER IS FAECES and plizz take all your format away from our n900.