[August 2010 Update -- IntelliGantt Web Part for SharePoint 2007 and 2010 is now available. Something we like to call 'The Worlds Greatest Gantt Chart']
WSS 3.0 and MOSS 2007 (which we'll call SharePoint in this post) have a great feature that lets you view any task list as a Gantt chart-- and a pretty one too. Here are the steps to make it happen:
1) Start with the basic Task List view
2) Next, click on the menu item 'Create a View'
3) Choose the Gantt View
4) Name it (and make it your default view, if you'd like)
5) Almost done, just have to set a few columns
6) Click 'OK' and enjoy the view
Of course, if you really want to get cooking with SharePoint services, I heartily recommend adding IntelliGantt Plus or an IntelliGantt Add-In for MS Project to the mix. It slices tasks and dices the amount of time it takes to serve projects to your whole team.
You'll be the hit of the party!