I have a bedroom and a living room roku. I do this, but you may not be able to watch the same channel in both locations at the same time - ie Netflix can play in the bedroom or living room, but not both.
Also, each unit has its own "bookmark", so you might have to fast forward.
Just to clarify: The bookmark features are specific to the channel implementation: A channel could store the bookmark in the device registry, or in the cloud. If it's on the device, then other devices won't be able to retrieve the bookmark, if it's in the cloud then all the devices associated with the account will be able to resume from wherever a video was stopped.
That's also true of how many streams you can access simultaneously: it's up the the channel creator(or content provider) to set the rules for number of streams however they want. Hulu only allows one. Netflix, in my experience, allows at least two. The rule for Netflix used to be # of simultaneous streams is equal to # of discs 'out at once' on your account. So if you had 3-out-at-a-time you were entitled to 3 streams. There is still a faq on the Netflix website with this indicated
(as of 8/11/11), but now that the streaming and dvd plans are uncoupled, I'm not sure what the rule is.