[iempty]

Is there a way to import / export address book from Firefox to an iPhone / iTouch ?

It seems that no, but perhaps you know a tip to do that... ?

[flyingember]

there's no way to do it directly. you have to either move/import your bookmarks to a supported browser or find an automated way to keep them in sync. there may be a firefox plugin to copy them to another browser

[impaler]

Actually (if you mean bookmarks), the best solution out there is Xmarks...which now works between Safari and Firefox.