Planning on travelling to Arusha and Zansibar in Januaru 2010.
I did a tour through Acacia Africa. We went through Arusha to Zanzibar staying in Dar es Salaam prior to boarding the boat to Zanzibar.
It is a good way to travel through these countries with the fees for the ferry over to Zanzibar and back included in the total cost of the tour.
I am sure you will be able to find some handy information or even a tour at www.acacia-africa.com about 10 years ago
Hi Kevin, I'm probably too late:( but I thought the following review of the Zanzibar crossing/adventure might be helpful for anyone else asking the question:
http://africastuckonyou.blogspot.com/2010/01/real-wanderers-contrasts-of-tanzania.html about 9 years ago