Adoption of mobile video is on the rise as is usage. A few interesting stats have been published this week.
Versaly launched a free (will begin selling/publishing ads this spring) channel (see channel 61) called Fast Lane on Sprint in January. Folks are downloading clips at a rate of more than 50,000 per week. There hasn't been a lot of free, ad-supported video content to date so I'm anxious to see how this goes.
MTV also announced that they are streaming more than one million clips per month.