I've assumed this but wonder about it. If I (or someone else here who isn't used to the menu layout) leaves a channel without pausing it, does the streaming continue? Since the Roku never shuts off, just snoozes after periods of inactivity, if it thinks you're still watching something (or a radio channel), will it continue to stream that channel even if you later select another one? Basically, can the Roku be streaming content from two channels?

As soon as you leave a channel the application stops and returns to the previous screen. So yes, it stops requesting/acknowledging content from the internet. You can stream content from two channels at the same time if you have two roku boxes, as that would allow two different IP addresses and two different instances of applications.