I've finally gotten around to fixing up cpsn to work against Sony's latest website version. CPSN is a cli app that lets you check if your PlayStation Friends are online, and what games they're playing so you can, for example, see if anybody is playing Call of Duty without leaving the comfort of your shell.
Install it with gem install --user cpsn
Check the included README for details on configuration.
Note: Using CPSN probably violates any number of Terms of Service, etc. Use at your own risk.