Is there a way to do a report against information contained in a workitem's history. For example, can we do a report of how many priority 1 bugs were opened that eventually got changed to a priority 2 or 3?

-Ed

Some work item history is stored in the cube and additional information is stored in the Warehouse. What question are you trying to answer with your report?

There may be a better way of doing this - and I haven't fully tested these, but for your example the queries below should get you started:

"How many priority 1 bugs were opened that eventually got changed to a priority 2 or 3?"
I translated to:
How many bugs are there which are revised and do not currently have priority 1 - and the 1st revision of the bug had priority 1.

Two Relational queries:

1) Using intersect:
use
[TfsWarehouse]
select
[Work Item].[System_Id]
from
[Work Item]
where
[Work Item].[Microsoft_VSTS_Common_Priority] = 1 and
[Work Item].[System_Rev] = 1
intersect
select
[Current Work Item].[__TrackingId]
from
[Current Work Item] join
[Work Item] on
[Current Work Item].[Work Item] = [Work Item].[__ID]
where
[Work Item].[Microsoft_VSTS_Common_Priority] <> 1

2) Using subquery:

use
[TfsWarehouse]
select
[Work Item].[Microsoft_VSTS_Common_Priority],
[Work Item].[System_Title]
from
[Current Work Item] join
[Work Item] on
[Current Work Item].[Work Item] = [Work Item].[__ID]
where
[Work Item].[System_Rev] <> 1 and
[Work Item].[Microsoft_VSTS_Common_Priority] <> 1 and
[Current Work Item].[__TrackingId] in
(
select
[Work Item].[System_Id]
from
[Work Item]
where
[System_Rev] = 1 and
[Microsoft_VSTS_Common_Priority] = 1
)

These do not exclude closed bugs.