Available Check-In-Policies for Team Foundation Server 2010

Shipping as part of Team Foundation Server 2010:
- Builds – Requires that build breaks that were created during a build must be fixed before a new check-in.
- Code Analysis – Requires that code analysis is run before check-in. [More]
- Testing Policy – Requires that check-in tests are completed before check-in.
- Work Items – Requires that one or more work items be associated with the check- in.
Supplied by the TFS 2010 Power Tools (needs to be installed on all VS clients):
- Changeset Comments Policy – Requires users to provide check-in comments.
- Custom Path Policy – Allows you to scope other check-in policies to specific folders or file types.
- Forbidden Patterns Policy – Prevents users from checking in files with filenames that contain forbidden characters or patterns.
- Work Item Query Policy – Requires that the associated work items need to be part of the result of a specified work item query.
Note: When using an older version of VS (2005/2008) you need to install the corresponding version of the TFS Power Tools (VS 2005 requires 2005 Power Tools, etc.)
Developed by the Community:
But what about the "Override policy" checkbox?

Further reading:
Do you know another great check-in policy for TFS 2010? Let me know!
Updates: