The question on a tool recommendation came from an audience member who said they had been using Rally, and end the end required one person full time just to manage the tool and data. KenKolcheir, who works for ThoughtWorks, obviously recommended Mingle, with a laugh, but I heartily agree it is a great, easy to use tool. Denise Phillips recommended VersionOne.
But the consensus from all the panelists was to keep it as simple as you can. If you can get by with cards on Post-Its stuck to a wall, do it. Also, this method provides a ready "information radiator" that helps visibility, communication and focus for those nearby or come and go interacting with the team. If you choose to use a the tools from ThoughtWorks, Rally, VersionOne, or Microsoft's Team System 2008, it would be very helpful to have a large monitor or fatscreen on the wall with your cards or a dashboard (with burndown, etc) as the information radiator.
I tried Post-Its, but switched to Mingle so our CEO could access the product and sprint backlogs from his computer and be more directly involved. This is what we needed and has been a key to the success of the organization really getting behind scrum.