After taking your first photo at an event, create a new album and name it something, say "Glass blowing in SF". That post will be created online and the first photo you selected will be added.
Now, throughout the day, continue taking photos. When you take another photo or video, you'll see this option:
Each photo you take can be added to the album you created earlier. The photo will be uploaded to Posterous when you take it, and appended to the image gallery on that post.
When you are done with that event and ready to go home, there's nothing more to do! Your photos and video are already online.
When you take photos, you'll automatically get this fast, good looking javascript photo gallery that people can flip through fast. We resize and host all the photos so you don't have to lift a finger.
When you send us video, you'll automatically get a video player that plays in Flash when viewed in a browser, AND plays directly from Mobile Safari on the iPhone (using Quicktime). We do all the hard work of converting your video to a playable format and and hosting it too.
No more sideways video! Vertical videos get shown properly.
Want to see more examples? See Sachin and Garry's photo/video blogs for how they use it.

PicPosterous with Autopost is the fastest and easiest way to update all the services you care about.
We support Twitter, Facebook, Flickr, YouTube, Picasa, Vimeo, and every major blog platform (Wordpress hosted and self-hosted, Typepad, Movable Type, Tumblr). For advanced users, if your custom blog supports XML-RPC, we support that too.
See Posterous Autopost Help or set it up here.
Albums are viewable in the PicPosterous iPhone app as well. Great for showing off photos while you're out and about.