Scott Wilson presented an interesting talk about presence and how the internet currently services these different aspects. In response to his comment about how Google wave is going to handle presence, I got 1/2 way through writing a response before realizing there's a diagram I could use to highlight the different points:
I've roughly coloured the slide with green for sections implemented in the current video, blue for where I think they'll want to be for release through integrating user's to google accounts, yellow for a harder implementation, mainly because it will rely on manual updates until the orange sections come online. It's alll possible with today's technology, but the strength of google wave's presence (as an email/IM replacement) will remain purely through a sense of activity.
Back to the question at hand about Google wave's ability to handle compartmentalisation, and I'm drawing blanks as to the most efficient method to implement it. The one technology that really had no issues with compartmentalisation was email as there was no presence to begin with apart from a diluted sense of activity. There was virtually nothing tying one email conversation to another apart from the time to respond. Once IM-like features are added into wave though, it feels like there should also be communication availability settings too as an adjunct to the immediacy of the conversation. Communication availability brings a much tighter bond between the waves though, and thus increases the issue of compartmentalisation.
Maybe the issue of availability can be broken down into separate specific goals? Availability can enhance the sense of activity by identifying to others when the user is focusing on their specific wave (not the wave client or the wave container). That would seem fairly simple using the 'wave reader' model where only one wave would typically be open at once, but what about a blog with 5 waves on the same page? IRC and IM have long forgotten the 'one conversation at once' mentality, so I would anticipate that even readers themselves would eventually have the capacity to follow multiple waves at the same time. Would writing in one wave indicate a loss of focus of the user on the other panes? Not necessarily.
When dealing with self-expression and facilitating casual interaction, compartmentalisation will really start to stick out. You want to have a cool looking icon for your buddies to see, but it may not be appropriate for the workplace. If waves replace forums, how many profiles would you have aggregated back to your wave reader? A status update might be possible to divert to a new wave sent to your 'distribution list', but that sounds messier. I'm not a big status setting person anyway, but one of the main factors is the simplicity of the action.
Maybe it's time we all donned a single identity? Maybe. Maybe it is part and parcel of who we are to express ourselves differently depending on the context and participants of the conversation? Maybe we just have multiple wave identities like we have multiple email and IM accounts? Lets hope not as I'd dearly love to have only one place to check ...