I downloaded the guestbook plugin yesterday, and I unzip it in the plugin directory. I go to the administration page of Serendipity but I install the plugin and nothing change on the Frontend page. I can't see where I am able to write a message on my guestbook !
Furthermore, I put the sidebar guestbook to se the lastest entries, and it is currently written :
"PLUGIN_GUESTSIDE_NOENTRIES"
If you did not change any of the defaults, your guesbook should be located at :
yoursite.com/index.php?/pages/guestbook.html (if you have URL rewriting disabled) or yoursite.com/pages/guestbook.html (if you ARE using URL rewriting).
Regarding the sidebar plugin, looks like there is a language constant containing a string to display when there are no entries in the guestbook, and that constant is not defined for your language.
