I apologize for the double post, got some bad news for everyone wanting the Top Sites update site indicator to work with Safari v6.
The short version is that the Top Sites site update indicator (blue curl with white star) is not supposed to work in Safari v6.0 and its a "feature" of v6.0 (meaning its not supposed to work) not a bug - also means its not likely to come back. 😟
The top sites web page update indicator uses the RSS functionality (yep the same one Apple got rid of in Safari v6) to tell if a page is updated or not, without RSS the page update indicator won't work - and part of this RSS functionality was actually integrated into OS X at the operating system level and was removed in Mountain Lion (this is why Safari v5.1.7 with RSS and top site indicator functionality crashes when launched on Mountain Lion...the backend RSS plumbing etc. that Safari v5.1.7 is expecting is not there).
Here's the page I found the information in the comments section about these details - serious bummer:
http://www.macworld.com/article/1168016/bugs_and_fixes_troubleshooting_mountain_ lion.html
As mentioned before, if you are running Lion, you can grab a copy of the Safari v5.1.7 package from Time Machine or another Mac (about 40MB in size and Snow Leopard did not get the v6 update) and copy it into a new directory (you create) in the Applications folder on your Lion Mac and it should run fine (with RSS and Top Site page update functionality...works for me). Be sure not to launch both versions at the same time as you could corrupt your user settings (since they use the same files for bookmarks etc.).
Mountain Lion users are stuck since the RSS functionality that the Top Site update indicator needs has literally been ripped out of OS X. Safari v5.1.7 will crash when launched in Mountain Lion because this backend functionality isn't there. For folks that are truly desperate, you could roll back (or reinstall) to Lion or Snow Leopard (although only Lion and Mountain Lion are getting system updates at this point) and then run Safari v5.1.7.
This is such a constantly used (the situational awareness of what page has been updated is so valuable) piece of functionality for me I will just run v5.1.7 for the time being (not a good long term solution since there aren't going to be anymore security updates for Safari v5.1.7, only v6...).
As far as I can tell other Browsers basically have what Safari v6 has, which is thumbnail screens of favorite sites with images that get updated (on some browsers - Firefox, Chrome?) and doesn't get updated on others (Opera) - but none of them has page update indicators like Safari v5.x. I wish one did have the Top Sites page update indicator functionality as I'd switch in an instant.
Total bummer watching this really useful and valuable feature get killed cause Apple wanted to strip out (web standard) RSS functionality from OS X and leaving the users in the dark about it all, as we try to figure out what happened. My sympathies to everyone who loves this feature as do I.