I’m on sharepoint designer training this week and getting up to speed to sharepoint publishing and WCM.
I spotted another bizarre default behaviour in sharepoint yesterday.
If you have a publishing site and you apply individual permissions to pages (also known as fine grained permissions), which is not beyond the realm of possibility on an intranet or similar website by default these pages will not be included in the search results.
Go to the site settings for the site and from the ‘Site Administration’ column select ‘Search Visibility’. You will notice that aspx pages by default are not indexed if they have fine grained permissions.
This just seems to be a bizarre default setting. Given that search results are security trimmed why is the default behaviour not to index all aspx pages?
Anyhow change the setting to ‘Always index all aspx pages on this site’ and they will be indexed.
The nice thing on the screen above is that the sentence above the radio buttons will indicate if your site has fine grained permissions.
Gavin's Sharepoint Blog 
The reason for this is that the summary displayed to the user will have been created by the crawler, thus may show a user something they cannot ordinarily see!
Apologies, ignore my massively wrong comment.
Hi Jon,
no probs and thanks for the followup comment.
I recently found out why the behaviour is like this by default.
In certain circumstances if there is a webpart on a page which exposes a items from another list and the items in the list have individual permissions then it is possible that the search results may expose information that the user is not meant to see. Of course when they browse to the page they will still only see what they are meant to see.
Cheers,
Gav