Is it possible to group my Craft plugins using the PSR-0 Standard?
Craft plugin naming conventions follow a specific format.

The plugin folder must live immediately under the craft/plugin folder and it must be the all lowercase name of your plugin's handle.

Your primary plugin class must live immediately in that folder and is named after your plugin's handle plus the word "Plugin".  i.e. PluginHandlePlugin.

Craft doesn't support any concept of multiple primary plugin class files in one plugin folder.