The Existence of Anti-SPIDs?

An astute member of the SQL Server community has observed the presence of SPIDs with a negative number. These anti-SPIDS were noted in SQL Server 2000 and appear to be generated by MSDTC.

I'm wondering if they behave like anti-matter and cancel out positively numbered SPIDs when they meet in a scheduler?

Comments are welcome.

For more information, see Rob Kraft's blog.