Hi Andrew - right now these apps display on their own individual URLs off of apps.yahoo.com - they're fully functional from a deployment point of view and can spread virally through user invitations. As you point out, the apps do not display anywhere else on the Yahoo! network at this time. We're currently working on building application containers into various Yahoo! properties - I expect that these will roll out steadily through the rest of 2008 and throughout 2009.
Eventually, you will be able to see your applications appear on My Yahoo!, the Yahoo! homepage, Mail and our vertical properties such as News, Sports, Finance, etc. - it's just going to take us time to roll all of that out.
How can we add our application to the list of apps that show up when a user clicks 'add content' in their my.yahoo.com page? Right now my app is in 'Live' mode, but i can't figure out how to get it to be in 'Gallery' mode.