Yeah, that's what they're pushing everyone towards: "you can sign up for Google+ right now to start prepping Reader-specific circles".
My bigger concern is the disconnect in sharing. Are they turning Reader into a one-way service, in that you share items to G+? It would seem incongruous to share things through Reader, but then have to go into G+ to see what other people shared.
It would be nice to have a panel inside Google Reader which would display only the G+ material shared from Google Reader - although I doubt they will do it that way. Anyhow, they surely will find a way to screw things up :P
This is getting into "architecture astronaut" territory, but Reader could have a "Google+" folder that aggregates "friend feeds" (of G+ status updates and shared articles). Does Google+ already publish RSS feeds for user content?
And they said they said they are integrating the two better, so I'm assuming its possible for them can make the sharing between the two fairly fluid.