The second part of the info on the API went up
D&D Insider: Compendium API - Part 2 yesterday.
One thing to note is that in my testing, null is needed instead of NULL in the filters. I saw the KeywordSearchWithFilters method the other day, but now that the filter strings have been disclosed, it makes it really useful.
Apparently they will be disclosing how to get to the data in a third article which addresses "security issues and concerns". This does indeed look promising and it is clearly meant for automation, but I still think that their TOS conflicts with the use of this. Perhaps it will get a refresh.