How?

Perhaps I'll post a more in-depth tutorial, but in essence:

Export original clip from Final Cut using Quicktime Conversion - Image Sequence (I used 15 fps frame rate)
Open an image from this sequence in Photoshop
In Photoshop, create an automated action based on this tutorial: tiltshiftphotography.net/photoshop-tutorial.php
Apply this automation to all the images in the sequence
Re-import image sequence into Final Cut
Voila! It's easier than it sounds, once you get the hang of it

ooh i wanted to know ho wthis was done thanks

Yeah, I was thinking 35mm adapter and tilt-shift lens - but this is way cheeper and maybe more fun to make :)

Wow, now that was spooky when the people are walking on the bridge.