Iceweasel remembers old java version (linux)

I had this problem already on several (debian) linux machines:
After updating sun-javaX-{bin,jre,plugin}, iceweasel/firefox still references the old (here: 1.4.2) version of java on about:plugins.

This can be solved by simply deleting the ~/.mozilla/firefox/pluginsreg.dat file while firefox is not running.
After that, firefox will re-create the file after finding the "new" java plugin.

edit:
Sometimes, there is still an old java version installed and the plugin is linked in the /usr/lib/mozilla/plugins folder (or any other plugins folder firefox looks in,
there are at least 3 on my debian machine¹ *gnarf*).
As Firefox simply tries to use the first it finds, you have to remove the link (or the old java version) before searching again using the trick described above.

¹ /usr/lib/{mozilla, mozilla-firefox, firefox}/plugins, ~/.mozilla/plugins

(via linuxquestions.org, thx craigevil!)