>>9
I'm mostly referring to the free desktop. A lot of projects are written in C, which takes longer to write and has a higher entry level to understand.
For example, look how quickly Banshee (C# I know, but fairly equivalent as a language) stormed past Rhythmbox in terms of features and contributors.
Same story with GIMP vs. Paint.NET - GIMP has arguably a higher profile and more users, but it's extremely difficult to contribute because of the learning curve. It only has a couple of contributors, and there's an age between releases. I'm sure the developers are doing their best, but if they were using a higher level language such as Java or C#, while pretty much speed equivalent to C, you can't help but think it would be much faster.
As someone said, if Java had had a free JDK earlier (or people weren't dubious of Mono's C#) it would have had a higher take up.