While pages are very interlinked, most people use ikiwiki for blogging. Blogging produces pages at random intervals and google apparently optimizes their crawls to fit the frequency of changes. For me it's not so often that the contents of my blog changes, so google indexes it quite infrequently. Sitemaps are polled more often than other content (if one exists) so it's lighter for the site and for search engines (yes, google) to frequently poll it instead. So it's not that pages can't be found, but it's lighter for the site to keep an up to date index.
According to [Google Webmaster tools](https://www.google.com/webmasters/tools/), my site isn't indexed for weeks at a time. Since I [blog](http://webconverger.org/blog/) every couple of days, that doesn't work. Yes I do have pingurl configured which [Google reader](http://reader.google.com/) does pick up quickly, but **not** the general search results from Google.
There is a [sitemap XML standard](http://www.sitemaps.org/protocol.php) that ikiwiki needs to generate for.
Update: I've since discovered under [Google Webmaster tools 'Subscriber stats'](https://www.google.com/webmasters/tools/subscriberstats), you can tell Google to treat a feed as a sitemap. Therefore in many cases just submitting your [[ikiwiki/blog/]]'s feed will be enough for Google to start better indexing your ikiwiki site.
