Nokia has released their open-source mobile phone server. It's running Apache, which seems kind of heavy-handed for an embedded web-server, but definitely full-featured.
Combine a local mobile webserver with the Opera Mini or Full Opera web browser makes for rapid development of nice phone applications.
They even offer some nice suggestions:
Interactive, Context and Location Dependent Content
These demonstrate that a website on a mobile phone is not just like any other website that simply happens to be on a mobile phone, but that it enables functionality that in the context of regular stationary websites is largely meaningless.
* Remote interactive picture taking.
* Use the phone as a webcam.
* Find other mobile web sites in the proximity.
* Find out the location of a mobile website (cellid).