Found a Bug in Team Build
I reported a problem on the MSDN TFS Build Automation Forum and Jason Pricket from Microsoft verified that it is, in fact, a bug in TFS 2008. My client previously hasn't used CI - so I setup the builds for the Application in TFS as "Daily Builds". Or specifically the build's "Trigger" is "Build Every Week on the following Days" with Monday through Friday checked. There's also a Check box for "Build even if nothing has changed" - which I have UNchecked.
The issue is that I have build automation using a task from MS Build Community Tasks that takes a version number from a Text File to ultimately update the Assembly Version, which I of course then check-back in to Version Control. Obviously, I don't want that check-in to be considered when evaluating whether "nothing has changed"
For CI, this would cause an infinite number of builds, so they added a feature where if you include "***NO_CI***" as a comment on your check-in, that check-in isn't considered when determining whether to trigger a build.
While having builds happen every night regardless of whether anything changed obviously isn't a serious of an issue as infinitely triggering builds, but this problem makes the "Build even if nothing has changed" useless - cluttering up your universe of "Builds" with unneeded ones. This could especially be an issue for Shops with lots of small applications that don't have a lot of development activity against them.
Of course - this is an argument for just turning on CI....
I reported this bug to Microsoft here. Forum post where Microsoft acknowledged it IS a bug is here