Is there a site or document that describes the current distribution of
usage statistics for broadband connections?  What percentage of use is
FTP, general browsing, media streaming, voIP, etc. and how the
distribution is expected to change over time?

You can look it up.  Try Voip-News.Com and at the top left under Voip
industry you'll see voip for dummies and voip migration see below:
http://www.voip-news.com/
http://www.voip-news.com/1/voipdummies1.htm
http://www.voip-news.com/art/1/toc.html

Something tells me you'll find everything you need and much much more.  John

Thanks for the links.  Unfortunately these sites seem to be
exclusively devoted to VoIP.  VoIP is only one type of application
that currently runs over the internet.  I was looking for statistics
that describe what the distribution of use for VoIP, browsing, FTP,
streaming, VoD, IM, gaming, etc.