Currently flair is offered on a per site (MSO, SO, SF and in the future SU).
Should their be a combined "piece of flair", or even better a simple XML that returns a users flair from all sites so we can roll-our-own flair display widgets.
Yes, I was just discussing this with someone else. I like the idea of being able to see multiple account details in one place much more than transferred or combined rep. The numbers represent slightly different things, after all.
It's possible that badge totals could be combined between the sites, however - the rep would give you a good general idea of how they're distributed anyway, and it would save having too much visual clutter.
Stack Exchange network profiles:
your network flair is available from the flair tab on your user page on each site. For example: