Idokorro (yeah I never heard of them either) just announced that they have released a Citrix ICA client for Blackberry handheld devices. It works on any color Blackberry device running v4.0 of the Blackberry system software or higher. The price starts at $35 per device and drops from there based on how many you buy. They're offering a 30-day free trial if you want to check it out.
The Idokorro client connects through a Citrix Web Interface server and runs published applications. If you're using a Blackberry Enterprise Server, then you can route all of your Blackberry ICA connections through it (just like any Blackberry app). You also have the option of allowing your devices to connect directly to your Citrix servers via their built-in TCP/IP stack and Internet connection.
I know that a lot of people have been looking for something like this for years. At our company, we use Windows Mobile devices instead of Blackberries. Has anyone out there given this Idokorro client a test? What do you think?