I think I read in a brewing book once that "Steam beer", is made by using lager yeast at ale temps. Anchor brewing were the first ones to commercialize this, and now we have the ubiquitous Anchor Steam Beer.
Not that this has anything to do with blending yeasts per se, but I wanted to back Yooper up on the assertion that if you stick to ale temps, both yeasts should still be able to ferment.