Backporting from sid

[+kenobi <jkkenobi@yandex.ru>]

Hello debian users

I have some backported package from sid (compiling from source package) 
on my woody machine.
1. How do i know which of my backported package have new version in sid, 
so i may do backporting upgrade?
2. How i can to know what new packages are added to sid that dont 
available in woody?

Thanks.