Yahoo360 and the Great Interaction Design Yardstick
What I really like about Jeremy's post is the repeated reference to Flickr when explaining things. The key thing is that Flickr (yes it is now owned by Yahoo) knocks the snot of of other's interaction design. Flickr set the standard and it is what many other web-based products are truly lacking. Getting the interface and interaction right is not half the battle, it is the battle. So few do it well and very few execs around the industry get that. What is lacking in so many products is design that creates, not just an ease of use, but a fun successful experience.
Flickr makes refindability of the pictures a person posts much easier by using tags that make sense to the person providing the tags. The interface for providing the tags is simple and does not take the user away from the interface (thanks to Ajax). The rest of the options are done simply from a person using the site's perspective. Everybody I know gets completely immersed in Flickr. This is something I can not say about Ofoto or other photo sharing sites, one goes to these sites to see the pictures somebody you know has taken. Flickr can be the most efficient photo sharing tool for uploading and managing one's own photos too.
Simply it is make things easy to accomplish tasks, focussing on what the person wants and need from the product. Accomplish this feat at the same time make it fun. There is no harm in making life enjoyable.