Recent Research
Much of the recent research in regards to M51 have been about supernova which have happened in the galaxy. There was one supernova very recently in 2005, which the Hubble Telescope was able to get excellent footage before and after the super nova. There also was a super nova in 1994. By observing these supernova in various wavelengths astronomers are able to classify them, and study the chemical composition and the motion of the gas from the explosion. Since super nova are billions of times brighter then our sun they can be seen from extremely great distances, and may be able to help astronomer chart the size of the universe.
This is an image from the Hubble Space Telescope of the super nova in 1994.
http://seds.lpl.arizona.edu/messier/more/m051_snhst.html
This image is also from the Hubble Space Telescope and documents M51 before and after the supernova explosion in 2005.
http://hubblesite.org/newscenter/archive/releases/2005/21/fastfacts/
Alot of research has been done on the black hole which is believed to be at the center of M51 since photos of the X shaped dust clouds that surround the black hole. For years these dust clouds were predicted by astronomers, but no one could prove that they existed because from our point of view you just saw nothing, and they obscured any view of the black hold. The new images gave the astronomers some more evidence towards their theories, and have proven to be a great asset in further research surrounding the black hole of M51.
http://findarticles.com/p/articles/mi_m1200/is_n24_v141/ai_12259546