Japan is in final preparations for the May 18 launch of its Akatsuki orbiter. This mission will use a innovative orbit to allow it to study the super rotation of Venus's atmosphere. While Venus itself rotates at a brisk walking pace (6.5 km/hour or 4 miles/hour), the upper atmosphere rotates at 400 km/hour. Current models of atmospheric circulation cannot explain the super rotation, suggesting that Venus can teach us some fundamental lessons about how atmospheres work.
The mission will study Venus in a number of wavelengths to study the atmosphere at different levels. One band will see all the way to the surface and will be used to look for signs of active volcanism.
Akatsuki's five cameras will be optimized to probe phenomenon at different levels of the atmosphere and on the surface. From Planet-C 2008 VEXAG update
The entire budget for the mission is just $280M (¥25.2 billion), although it's not clear what all is included in that cost beyond the spacecraft (launch vehicle? instruments? mission operations?). Whatever the full burdened cost of the mission, it appears to be within the scope of what would fit within NASA's Discovery program. This suggests that there are still interesting missions to the inner planets that would be relatively inexpensive.
As the launch date approaches, articles are beginning to appeal, and I posted a blog entry on the mission some time ago that includes some nice illustrations:
My blog: http://futureplanets.blogspot.com/2009/03/vexag-part-2-japanese-venus-climate.html
Journal Nature: http://www.nature.com/news/2010/100315/full/news.2010.126.html?s=news_rss
Aviation Week and Space Technology: http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=space&id=news/asd/2010/03/18/04.xml
JAXA Planet-C website
Planet-C 2008 VEXAG update (with information on scientific goals)
Planet-C 2009 VEXAG update (mostly engineering and schedule) Large file!