This article on The Guardian by Seth Shostak, Senior Astronomer with SETI, is worth reading. It combines the concepts of the search for extraterrestrials and transhumanism (though the latter isn’t labeled as such). The author does leave open the possibility that machines will never outstrip human intelligence, but only apocalyptic scenarios can prevent it since “if any species reaches the point of inventing radio, it is only a handful of centuries from inventing its intellectual successors”. (Kurzweil says it will happen in 2045.)
Shostak points out how movie aliens usually have faces like we do, which is just convenient movie-making. He also sets apart biological and machine intelligence. But just as it’s not very realistic to assume aliens have faces, isn’t it also folly to think we can imagine what form intelligence will take after millions or billions of years of development? If sentient beings obtain a fine degree of control over their evolution, whether the “hardware” is biological or not becomes moot. Certainly our most advanced computers would seem more primitive to them than stone tools do to us.
Shostak says that we shouldn’t be looking for intelligent signals just from Earth-like planets – and given his job title, I assume he can broaden the search. If you have the time, some nice counterpoints made in the article’s comments.