Thanks for answers.
I'm running Elyssa with default repos with few tiny exceptions (lastfm for instance). I've updated manually pidgin to 2.5.2 and I'll probably do the same for FF if it does not show in mintupdate this month. But I'll go for a .deb instead of "pollute" Mint with ubuntu depots
I've started my "virtual Felicia" and FF 3.0.4 is available thru mintupdate ... Why isn't the case with Elyssa ? It's not like saying that FF 3.0 is bundled with Elyssa and 3.1 will be the default for Felicia, we're talking about a security fix on the default bundled 3.0.x FF.