I've committed two new plugins to the repository. First the serendipity_event_markread ("Show read/unread state of entries for visitors"), which is a plugin that allows to you mark entries as read for your visitors. Just as the description says *g*. This is very usable for aggregator-sites; the plugin offers new smarty variables (look at the PHP code for info) so that you can custom style your entry layout depending on the read state of an entry.
You could, for example, show the extended body for all unread entries, and only show the first 20 characters for all read entries. Use the power!
The read state is saved in an additional DB table and sets a cookie to remember your visitor ID. If you're a registed author/user of a blog, it will set your cookie in a way that you can also log on to other computers where the read state will also be carried over to. As anonymous user, your read-state will be per-computer.
The second plugin is serendipity_plugin_showentries ("Show entries in sidebar"). It allows you to show an entry listing with body texts and so on of certain entries inside the sidebar. You can show entries of a specific category there, which makes it great for moblogging sidebars, where you can fetch all entries of a "Moblog" category
Have fun and a nice weekend, Garvin