this might be the most ridiculous idea you have ever heard, but does babel have a concept similar to stdio pipes? i've often wanted to just pipe stuff. dunno if this would help marcin.
the only inter-block communication i am aware of are variables and noweb inclusion. [and, unless i am mistaken, one or the other inclusion mechanism always outputs intermediate lines of text as messages in the minibuffer, dunno if that can be turned off.]
