I wondered how long it would be before folks outside of the DSL Tools/VSX/SF community started to pick up on the fact that T4 is in every VS box as of VS 2008.
Here's my answer...
Kirill Chilingarashvili has a nice example of turning some weakly typed data into strongly-typed data and hence moving errors from runtime to compile time. Rarely a bad thing. Interestingly this doesn't even require a directive processor to be written to get the data into the template.
Nice stuff Kirill.