UPDATE: Since putting this article together MS have released their VS2010 and MSDN Licensing White Paper, which whilst it confirms all of the following should be used in preference to this information.
Firstly, a bit of a disclaimer - the following are just my observations / opinions only and should not be used to plan any purchase or decision. I also have no association with Microsoft or any reseller.
As part of a new role I've recently been looking into the costs associated with rolling out TFS 2010 and whilst Microsoft seem to be making their product structure / licensing easier if the confusion surrounding TFS is anything to go by then they've still got a little more to do.
There are two main ways to obtain TFS:
- As part of VS2010 + MSDN, or
- As a stand alone product.
As far as I can ascertain both include exactly the same version of TFS. Along the VS2010 MSDN subscription a developer receives 1 Client Access License (CAL) for use with TFS. This allows that developer to connect to any instance of TFS. The stand-alone TFS product does not come with any CALs, these must be purchased separately. However it does come with 5 EULA exception licenses (see following blog article). This allows up to 5 users to connect to that instance of TFS without needing a CAL. Note: you can not coalesce / merge these EULA licensed exceptions in that if you purchased two instances of TFS you would have 2x5 EULA exception licenses - if you had 4 users on one instance and wanted to add a 6th user to the other instance you would need to purchase a full TFS CAL for that 6th user, you could not transfer the unused license from the 1st instance to the other server. Also worth noting that in this scenario the 6th user that has the CAL would be able to use the 1st instance without using up that 5th EULA exception license.
Therefore if only developers are going to be accessing / using TFS and they all have MSDN subscriptions you do not need to purchase the standalone product. However, if you wish for product managers and testers to access / use TFS, then you should probably purchase the stand alone product too, then up to another 5 people can connect to that instance of TFS along with the developers.