I have not used it in a few weeks and the phone has been on/off a few times and it is still there.
It is using 6.2Mb of RAM, which isn't exactly crippling the phone... I am just curious as to what it is doing there.
I got a PM to tell me that it is merely storing its last known status so it can boot up faster next time... but it does seem strange that you don't get any background processes. Are you logged in to Waze when you close it?
EDIT: I have just run Waze and switched it off in the settings and the background process is still there.