Some interesting links with unity tutorials for 2D sidescrollers

 This is a pdf tutorial that come with a project file to help familarise yourself with 2d game mechanic i believe

 PDF:-
http://en.youscribe.com/catalogue/manuals-and-practical-information-sheets/knowledge/others/2d-gameplay-tutorial-20080219-211540

 Downloadable game project :-
https://github.com/irtemed88/unity

Youtube tutorial for 2d Platformer:-
http://www.youtube.com/watch?v=d3HEFiDFApI

youtube tutorials:-
http://www.youtube.com/watch?v=1UQqbMBKq-M

this has some interesting character mechanics such as ducking

http://www.youtube.com/watch?v=MTmxo7L9ytA