Another link:
http://www.xml.com/pub/r/1040


"
JSP is well understood and deployed, and what developers already know is a major consideration when ramping up for a large development effort. In this kind of application, or when trying to get a project out the door expeditiously, JSP may be a better solution. XSP delivers the best method yet for clean separation of presentation from content. This is a labor and time saver on any project, allowing teams or individuals to concentrate on a specialty and process in parallel, but it's especially important when developing XML applications. JSP is powerful and has made major strides towards, but hasn't completely realized, that separation. Like HTML, it will still mix data with presentation.
"

see:
http://www.onjava.com/pub/a/onjava/2001/02/22/jsp_servlets.html

"If your main concern is getting a product out the door with the least risk factor, then JSP is your answer.
JSPs are popular and widely understood, while XSP and Cocoon are still emerging. This is not something to overlook. For large scale projects, it is always necessary to evaluate how much effort it would take to bring a new developer up to speed and the pool of talent you can draw from. In addition, existing HTML and XML tools can be used for JSP development, making the overall time it takes to get rolling relatively short."