blt shows you what your twitter friends are doing while you're working at the commandline, in Linux, FreeBSD, OS X and Cygwin under Windows. In more detail, it's a perl script which integrates the checking of twitter into bash.
Think of it like biff for twitter. It should be considered pre-alpha at present. blt is released under the GPLv3 with no warranty.
marnanel@charcoal:~$ firefox &
< wombats > deliriously happy
marnanel@charcoal:~$ blt @wombats: watch out for her siblings
Copy it to /usr/local/bin or similar. You will need the XML::LibXML and YAML libraries installed; they may already be installed on your system. There will be an installer one day. Let me know if you have problems.
blt is automatically set up based on questions it asks when you first run it, but you may set it up otherwise using the YAML file ~/.bltrc. It also attempts to add itself into your ~/.bashrc with the code PROMPT_COMMAND=path-to-blt. There is a rate limiter stopping blt checking twitter too often, which can be configured, but only by changing ~/.bltrc at present; it currently checks at most once every 60 seconds, although you should be aware that checking more than every 52 seconds on average is a TOS violation.