Caught this thread yesterday evening and thought it would make an interesting project. Decided to model one and am offering it as a freebee. 
Morphable Poser prop to open or close, obj and pp2 included. I've only assigned basic diffuse colors to it but have included a UV template in the .zip.
Feel free to use for commercial or non-commercial projects.
http://www.sharecg.com/v/11119/3d-model/Morphing-Umbrella

Hey! His nose is dry! ... Someone should lick it,  just in case. - Diego