You can have an IM sent to your Google Talk / Jabber account whenever there's new activity on your FriendFeed. Once you have enabled IM notifications, you can also post messages and comments to your FriendFeed by sending IM commands to the FriendFeed bot.
FriendFeed assigns a number to your most recent entries. You can use this number to comment on or like the entry. See the commands below for some examples.