Disclaimer The opinions expressed herein are my own personal opinions and do not represent my employer's view in any way.
I met up with the Altova folks last week at Tech-Ed and asked about any cool improvements or features in their 2009 version of DiffDog It turns out there are two new, albeit surprising, features in there: compare and merge (the contents of) database tables.
It looks pretty good, and very similar to Microsoft and Red Gate’s products – just surprising to see it in an XML compare/diff tool.