What are the laws regarding this in Washington state, and what does it even mean? Are you only allowed to fish with so many rods AT ONCE, or are you only allowed to carry so many with you PERIOD? 

^{Your question is best directed to your FWC as the rules vary depending on fishing location.}

I believe now in our state, you can purchase a 2nd pole permit.  Not sure of the price, but I don't think it is very much.  It used to be 1 rod only.  With the permit, I believe you can fish with both at the same time.  This is probably more aimed toward bank fishermen and trollers.  As far as how many rods you can have with you, there is no limit I believe.  I know I carry 12 or so on my boat as do most bass fishermen I know.