I starting to work with Ruby and Soap and had some questions:
How do I generate a WSDL file for the service I created? Will it be compatible with an .NET client ?
ActionWebService (previously in Rails core, now a gem) has tools to generate WSDL files. You can use the tools even if you're not running your service within Rails.
http://www.datanoise.com/articles/2008/7/2/actionwebservice-is-back
As for whether it will work with a .NET client, the answer is maybe. Many .NET clients seem to expect Microsoft's "extended" SOAP info, which .NET webservices provide by default. If the client is also able to consume a service without that extra stuff, then sure.
The above link no longer appears to work. There are however forks of ActionWebService that have popped up over on github. You can see a pretty good list of them here. Here are a couple of links to some key versions: