To everyone asking "why" or "what for", please read [1] and [2]. The data behind may not be as abundant as other studies, but the conditions are met in Venus and extremophiles could already be living in the upper atmosphere. A mission like this one could potentially take exobiology from theoretical to empirical.

Alternatively, we could take extremophiles cultures from earth, take a sample of venusian atmosphere, and study their survival in such an environment -- of course, taking care not to contaminate the atmosphere.

[1] http://web.archive.org/web/20110807004311/http://gltrs.grc.n...

[2] http://en.wikipedia.org/wiki/Atmosphere_of_Venus#Possibility...