I was just asked a question on how to pass usernames between web servers (Domino/WP/WAS to another non-IBM web server that needs awareness) if the environment has Siteminder deployed. The easiest way to pass valid usernames in an environment with Siteminder is using Agent Responses configured on the target agent(s). The response basically adds a custom field to the HTTP header which can then be parsed/looked up from the JSP/PHP/.NET/CGI/Python web page. The response can gets its value from an LDAP Attribute or can compute a value, which could be the user DN used by Sametime. Refer to my Siteminder articles on developerWorks for more information on Agent Response.
For example - PHP page could use $_GET['http_customvar'] or request.getHeader("http_customvar") in Java.
Here customvar is the name of the Agent Response variable being configured for the agent (and we use http_cutomvar to refer it on the target web servers).
Raj Balasubramanian, ISSL