One of my colleague introduced me to Openlaszlo today and I should say I was amazed by what all you can do using Laszlo.
This is what the Laszlo has to say about OpenLaszlo :
OpenLaszlo is an open source platform for creating zero-install web applications with the user interface capabilities of desktop client software.
OpenLaszlo is write once run everywhere. An OpenLaszlo application developed on one machine will run on all leading Web browsers on all leading desktop operating systems.
The OpenLaszlo Compiler compiles LZX source files into executable binaries for targeted run-time environments. The OpenLaszlo platform currently targets the Flash Player and soon DHTML.
More on the architecture of Laszlo can be found here.
OpenLaszlo Technology Demos
XML Editing – Tutorial on Laszlo XML markup language
And yes, Eclipse does have a nice IDE for creating, editing, debugging, and testing applications based on the LZX declarative mark-up language. The IDE for Laszlo is a joint project of IBM and Laszlo Systems.