If you are willing to code your own WML, we use Apache's Tomcat
(http://jakarta.apache.org/tomcat/index.html) as our server (it can
run standalone, or in conjunction with IIS or Apache's web server -
we use it standalone in development and with IIS:[ in test &
production). You can detect the type of browser (HTML, WAP, etc)
from the request and set the appropriate Content-type for the
response. We do that in a reusable architecture layer (our servlet
class extends HttpServlet), which makes it easier and quicker to
write the servlets (I've timed some, and without interruptions I can
code database reports, SQL and all, in 1hr 5min, and updates in less
than 1/2 day). The servlet code is fairly simple - there's one
method that contains page selection logic - the page/deck to be
displayed is based on the parameters in the URL and/or form input.
Then there's one other method for each page/deck to be displayed. I
played around with subclasses that would generate either HTML or WML
from the same method calls, but found that it was better to write
separate code, due to the smaller screen size of WAP devices. About
the only place the other approach might be useful is in a menu system.
If you've coded CGIs in C++ or perl, the logic is pretty similar.
You can view what you're programming as individual transactions:
input -> processing -> output -> (done). However, you have a bit
more flexibility than with single-page technologies (PHP, .asp, etc)
and Tomcat maintains a session where things can be stored/retrieved.
There's also a lot of info on the web, as well as books on it.
Apache has a lot of good Java stuff in the works....