I don't like the contact list concept. Mainly because it just wouldn't work too well. Reason being, well ask yourself this "how many people do I know with short names in my contact list?". The amount of space that is given for the contacts name is really small. Like I know the iphones icons are like that but it isn't really practical for a Messenger contact list where the length of ones name will vary a lot.
After 5 letters the name would get clipped and that can get annoying for those contacts who have symbols and stuff in their name. I know you have it over two lines but I don't think the text can be made to do that in Messenger.
The real time clock isn't possible with native skinning, however if you write a script it might be. Thats about it, the rest should be possible.
But of course you still need to think about how the chat window will work and stuff like notifications and contact cards
so yeah.
/ 
