I have been using log-deprecated-notices to monitor the plugins that I am using with my main website.
I have been surprised how many plugins have deprecated calls (including a coupkle in the WP 3.1 RC4 core) and so I have have been sending 'heads-up' posts to the developers of my favourite plugins. It occurs to me that it might be quite straighforward for you to add a feature to l-d-n that makes this 'head-up' process easier.
For example, if I could easily grab summary of all the deprecations related to a single plugin I could better inform the developer. Or perhaps send him/here a url to a file on my website that had the same effect.
Of course, it would also be most helpful if there was a link in the deprecated report that took me directly to the plugin/developer website/email address.....
Seems to me that this would be a good service for both WP users as well as plugin developers?