Google Sitemaps continue to improve

I've noticed that the information in Google Sitemaps continues to improve. For instance in the list of search terms and the average top position which is something that previously was quite tedious to figure out (search and then click until you find your page referenced...) It also gives content analysis of your site, and analysis of incoming links to your site (what words are there.) The average search term rank though is probably the most valuable addition I see. They've also....

Added a summary of pages with the highest page rank by month, which I hadn't noticed before (it goes back to February for one site, so maybe it coincided with "Big daddy". My biggest wish now for the sitemaps interface is an explanation of "why my site does not show up in the index" instead of the usual blanket explanations, it would be nice if sitemaps could be used as a direct channel of communication about 1) what, specifically, might be wrong with a site and 2) how to remedy it. or even 3) request a re-evaluation after changes have been made.

On another note, I've found one of the sites I host has a WRONG entry in Google cache. They have the domain address right, but the content summary is for some other site. Additionally, the cache was VERY recent (last month) the site has been up for 6 months or so. It's not a web-defacement kind of cache, just a "wrong site" cache. I think the account is on a shared IP - I'm wondering if there's something funky going on with the way they pull data to cache from shared IP servers (maybe they're caching by ip address not by domain name? so the server doesn't know whose page to throw out to Google?....)

I've now verified this with three "shared IP" accounts. Wrong cache site and wrong page summary. I've listed the ones in particular to Google. (You might imagine how big a problem this could be for a site owner...)