today I installed this plugin using the "Plugin"->"Add new" page in WP 2.8.4
The installation was successfully but then, the activation failed with the following message:
The plugin does not have a valid header.
I tried again, uninstalling it, then installing again and activating it, again the same error.
This happens if I click the "Activate Plugin" link at the end of the installation page, where I see the installation report:
Downloading install package from http://downloads.wordpress.org/plugin/postlists.zip.
Unpacking the package.
Installing the plugin.
Successfully installed the plugin PostLists 2.0.2.
while the "Activate" link in the plugin page works fine.