I've been watching the AI scouting and it is kinda weird.  I saw two races' scouts come through my territory.  Rather than going start to star mapping the planets.  They went in a train 4 long (both teams) about 10 parsecs apart.  This just went in a more or less straight line through my territory.  If (as has been alledged) the AI needs to scout before sending in colony ships and constructors, this seems really suboptimal.