Here is a nice article show a sample of using XML and CSS to build and style swing application.

http://weblogs.java.net/blog/enicholas/archive/2006/03/style_swing_com.html
http://weblogs.java.net/blog/editors/archives/2006/03/i_want_to_break.html

However, there are some framework doing work in reverse direction, from markup to API call: http://jakarta.apache.org/ecs/index.html

I think it is hard to have an absolution better choice to do UI. However, I will have a feeling that using API call approach is likely to have better reusability. As we already build up a lot of OO pattern to help our design. What do you think?

[more info: http://beust.com/weblog/archives/000377.html ]