T-SQL Procedural Blog
I ran into one of my colleagues in the hallway the other day from another part of the product, and he told me about the blog that the Programmability team has been doing.
Effectively this is the compliment in the expressability story to what we do in queries. So, there are a lot of details about various functions, how T-SQL works in more detail, etc. If you need help with those issues, please check out their site.
There are some very interesting areas where the two intersect, actually, and I'll try to get some entries together about them in the future (for example, user-defined table-valued functions).