I have been able to deploy a few Silverlight applications which use WCF RIA Services with success. Look here
for one of my previous posts about deployment. One issue came up today that I thought was worthwhile to share.
We created a website in IIS 7.5 which contained multiple bindings (e.g. www.mysite.com and mysite.com). The site ran fine but my Silverlight application (using WCF RIA Services) failed. When I removed one of the bindings my application worked fine. WTH??
In the web.config file under the System.ServiceModel node we added the attribute multipleSiteBindingsEnabled="true"
to the serviceHostingEnvironment node. Once this setting was added everything worked fine under both bindings!