Fleets blockading ports indefinitely is a bug that was solved with the latest patch I think (or I guess anyways since I didn't really read much, other than 'AI improvements')

This situation here had been going on for 40 or 50 turns: http://cloud-2.steampowered.com/ugc/...9F081D8E071EE/

Once I loaded the game after installing the patch, the first thing that happened was a funny battle that involved 5 different factions ^^