This plugin performs the following tasks:
Delete all posts and/or comments in selected category
Move all posts from one category to another
Plugin was developed for may needs so its functionality is quite limited right now. However i plan to add more and more features to Mass Post Manager
Uunzip, upload to your wp-plugins folder;
In wordpress admin area go to Plugins and activate mass Post manager
Go to manage -> Mass Post manager to see the interface
It is very useful.