Why isn’t Russia invading?
Perhaps the biggest puzzle piece missing is Russia: why didn’t Moscow leap all over Bishkek’s invitation to basically invade Osh? My guess is because Medvedev et al actually perceive the proposed constitutional reform by Otunbayeva et al as sincerely parliamentarian and democratic, so they’re using the riots as an opportunity to sit back and let the whole process crash down.
(Of course, you might ask: why didn’t Bishkek just ask for help from Washington? Well, practically-speaking, Russia’s just closer, and besides, it was the halal thing to do. Moscow’s already displeased with everything going down in Kyrgyzstan.)
Another idea: Perhaps Moscow is just playing coy, or letting Bishkek get really uncomfortable first, just to remind them who’s boss.