i have a very simple winform application in vb.net and i was wondering how do i make it work on blackberry and other PDAs?
Unfortunately this is not possible. There is no version of the .Net runtime available for blackberry devices.
If it is not be too difficult to convert your Winforms application to ASP.NET, you could use that on a Blackberry ...
Flowfinity Blackbird is an add-on to Microsoft® Visual Studio® 2005 that empowers ASP.NET developers to deliver "Wireless-Ready" applications for BlackBerry®. Using unique features of Visual Studio 2005, Blackbird shortens the BlackBerry application development learning curve for Microsoft .NET developers.
It's not exactly what you're asking for, but it might help. Also, check out Windows Mobile. That might fit your needs as well.
I haven't tried it personally, but you may look at a language such as Scala and see if you can compile code in that language for a JVM that will run on a Blackberry. One advantage is that they are working on having it output CLR bytecode also, so, in one language, you can go between .NET and Java, but, then the Winforms part will be problematic, but not insurmountable.
If it really is a "very simple" application, you port it to BlackBerry's version of J2ME. Since both are managed languages, it shouldn't be too difficult.
Check out the MDS runtime and VisualStudio plug-in which you can download here: http://na.blackberry.com/eng/developers/rapidappdev/devtools.jsp
I am finishing up development of a plugin for my VBeeJ For Java translator to translate Windows Mobile apps to native J2ME Java which uses the Blackberry UI controls. We are working with a client with a fairly advanced app. Current status: delivering app to client, for the Blackberry.
Yes, you can develop on .Net and run native on the Blackberry. Contact for estimate. http://www.beelucid.com
See http://code.google.com/p/csharpblackberry/ As for VB.Net development, am busy with a prototype.