I have been around looking for possibilities.
I have 3 virtual domains, domain1.com, domain2.com, domain3.com. They should login to RC on a single page. After they login, their RC UI should appear it's own logo. domain1.com has roundcube_logo, domain1.com has it's own.. and so own.
(sorry for bad english) you get the point right?
From previous thread of Gus with "Custom Logos and Welcome Text based on domain name" i got the idea.
Hope for your help here..