We were originally going to do photos in the same way as WildlifeNearYou - ask people to auth their Flickr account and associate photos using a picker.
It's pretty clear that the "paste in a URL" mechanism is much more approachable than we had thought, so I think we'll probably try and do something sensible with the Flickr URLs we are getting at the moment combined with the Flickr API.
Embed.ly actually supports Flickr URLs, but it returns weird Flash slideshow things that weren't really what we were after so we turned those off.
Simon, it's a perfect use case for PubSubHubbub :) Susbcribe to the feed for the right tag and get notifications as soon as new pix are uploaded with the right tag!
http://lanyrd.com/2010/startup-school/coverage/
http://lanyrd.com/people/paulg/video/
http://lanyrd.com/topics/django/slides/
We're using http://embed.ly/ to pull in the Vimeo / YouTube / SlideShare embed codes.