I’ve been fiddling with Django a bit in my spare time recently, with a view to possibly using it for some side projects. It’s the Python web application framework, similar in many respects to Ruby on Rails but with a distinctive flavour of its own.
Another good thing about Python is that it is very much an all-rounder: like .net or Java, you can write web applications, console applications, services, GUI applications, maintenance scripts or whatever else takes your fancy with it. This is in contrast to PHP and Ruby, which tend to be dominated to a much greater extent by web development, though they are capable of being used for other things. Python also has fairly mature support in the .net ecosystem — IronPython is the most mature of the DLR languages, so integrating Django with .net framework code is a real possibility. It also seems to have a much smarter contingent of users on average than either .net, Java or PHP. I think this is because it is only infrequently the first programming language that people learn, and most Python developers already have quite a bit of experience with two or even three other languages.