One of the most common requests we've had with regard to TFS licensing, is to make it easier to license occasional users of the system to enter work items such as bugs, requests, requirements, etc.  Up until now, anyone that even wanted to report a bug had to have a TFS Client Access License (CAL).  Since that requirement is somewhat onerous for someone that might enter a bug or two every year, with TFS 2008 we have extended the right to everyone in your company to create any work item as well as query, view and update work items that they have created without purchasing a TFS CAL.  Folks that want to make more extensive use of the work item tracking system within TFS, such as querying and updating work items created by others will still need to purchase a CAL.  We're still working on making this limited functionality easier to enforce so that customers know when they're in compliance and hopefully we'll have a good solution to this sometime in 2008.  To learn more, please refer to the EULA that accompanies TFS Standard Edition as well as Brian's more detailed explanation.