It would be great to have a plugin that will obtain compatibility information for all your plugins in relation to the available WordPress update.
For each plugin it would show the max version the plugin is compatible with (as shown on the plugin's page here on the WP site), and it would also show the Works/Broken ratio.
It would then calculate the total % of plugins that are compatible with the next available version.
Eg. if I'm running 3.0.5, and I check the plugin compatibility checker page, I could see the compatibility of each of my plugins, and an overall compatibility percentage (eg. 70%).
Any takers? As far as I've been able to find, this doesn't exist.