Pidgin can log in to multiple accounts on multiple IM networks simultaneously. This means that you can be chatting with friends on AIM, talking to a friend on Yahoo Messenger, and sitting in an IRC channel all at the same time.
By default in Ubuntu 8.04 pidgin instant messenger will come as built-in.If you want to enable Pidgin Plug-ins it is very easy now.
First you need to login in to pidgin messenger now you need to select Tools--->Plug-ins
Now you can see the list of available pidgin plug-ins as follows
If you want to install particular plug-in select the plug-in check box and click on Configure Plug-in
It will show you the available options for this plug-in select and click on close
You can also install plug-ins from pidgin icon from notification area
Now you need to right click on pidgin icon select Plug-ins