Has the 'Arab Spring' Come to the Russian Winter?

Russian authorities did not clamp down on massive protests in all that country's nine time zones over the weekend, despite repeated shouts of Vladimir "Putin is a thief" and "Russia without Putin." Today, the billionaire Mikhail Prokhorov announced he'll challenge Putin in next year's presidential elections; the former finance minister Aleksei Kudrin said he'll form a new party to push for liberal reforms; and the Russian Orthodox Church called for election reform. We hear about Saturday's mass protest and political challenges from the left, the right and even the Orthodox Church. Is Putin really at risk of losing his power?