Create a private mediawiki with some public pages

Per site restriction is not possible by default in mediawiki, but there are many ways to create such environment mostly with using extensions. The most easy and flexible way without extensions is described on this page: http://meta.wikimedia.org/wiki/Regexp_wgWhitelistRead

It’s simply done by editing the file include/Title.php and find the line that looks like this in the function userCanRead(). In my version 1.16 it looked minimal different than at the link example:

Replace them with the following lines:

Then you are able to use regular expressions in your $wgWhitelistRead which offers great opportunities.

The following code allows non-namespaced pages, Special:Search, Special:Categories pages and several Namespaces like: Help:*, Image:*, User:* and Category:* to be seen by anonymous users.

If you really have a private Wiki you might also want to remove Search and Categories, as they list also your private pages.