I have been working with lot of ISV vendors who looking to become Citrix Ready and get their product listed on the Citrix Ready Catalog.

One common problem they sometimes face is how to verify their application works with Citrix/Terminal Server. Microsoft Terminal services team has written really good blog post and posted a tool.

Here are some short cut links which you will find useful regarding Terminal Server Application compatibility

1 How to develop Applications for the TS and Citrix Platform
While most 32-bit and 64-bit applications run “as is” on Windows Terminal Services, some do not perform as expected due to differences in the platform between Vista and Windows 2008 Terminal Service

2 TS Application Analyzer
TS Application Analyzer is a runtime program analysis tool to enable administrators/users to determine if they can deploy an application on TS with confidence

3 TS Programming Guidelines
The TS Programming Guidelines provide information on how to design your application to ensure that it runs smoothly on Terminal Services and provides a rich, seamless, and integrated experience to your end users.

4 White paper: Application Readiness for TS
The TS Application Compatibility Connect program is aimed at providing content and tools to address application compatibility issues and to enable you to readily deploy your applications on TS. Anyone can join the Connect program to learn about ensuring

Please contact CitrixReady at citrix dot com if you are interested in becoming a Citrix Ready Partner.
Do you know of any other links or tools which can help with TS application compatibility issues?

UPDATE
check out blog by Vinny Sosa on Citrix application compatibility toolkit and and other resources

UPDATE 2
How to Effectively Troubleshoot Citrix Application Integration and Compatibility Issues?

*http://support.citrix.com/article/CTX101709*

UPDATE 3
Best practices for windows developers writing Seamless Application for Citrix