Yeah, I also like it when there are good examples.
I've extracted graphics1.gtp to see what changed for those block"e" models (they are actually new, weren't there for 1.026) and it seems that texture's alpha channel is somehow used for specularity. At least this is the only obvious difference between them and old models.
The manual states that only 0% and 100% transparency is supported on buildings, so maybe values in-between define specularity?
Of course, an official answer is preferrable than my guesses