Venus Express Delayed; Mars Express Lonely

The European Space Agency's launch of Venus Express, sister ship to Mars Express, has been postponed for "several days" following detection of "contamination" inside the fairing--the hood that covers the payload.
The probes mission is to map the surface of Venus, study and track weather patterns and atmospheric composition, but perhaps most importantly to analyze the planet's magnetic field and determine if the lack of one has created such an inhospitable environment there.
The Soviets had some successful missions to the Venusian surface, with Venera landers that lasted several hours before succumbing to crushing pressure and blazing temperatures. And the United States collected some juicy data with the Magellan Mission, and the earlier flybys by Pioneer and Mariner.

It's not likely we'll ever take to living on the surface of Venus, where daytime temperatures reach a sweltering 450 degrees Celsius, but maybe we can learn why a planet so much like ours in so many ways, is also dramatically different.