Not wanting to offend TB or insult his work as have lots of respect for both, so I'll just lay down a fact and see what you guys think.
The Stuffplug build in testing currently 'can' offer Tabbed Chats and I know that Scripts/Plugins were being developed too.
Although they are implemented differently and SP Scripts (I believe) have access to more of the internal section of Messenger, potentially allowing buttons and stuff to be added within menu's.
Personally I don't think this is stealing, as they work differently and will use different code, and should co-exist quite nicely, tabbed chats do need some more tweaking currently, that's if they even stay in I'll assume the same goes for scripts and content, personally I can't wait to help TB create some Dynamic Content, you might even see me make some clay based work for messenger
/ 
