You've heard of LAMP (Linux, Apache, MySQL, PHP/Python/Perl). You may have also heard of WAMP (substitute Windows for Linux as the OS platform). WISP is Windows, IIS, SQL Server Express (or full package), and PHP. SpikeSource put together a bunch of pre-built WISP bundles that include preconfigured applications of various kinds: WISP+phpBB, WISP+Moodle, etc. I'm doing some blogging for O'Reilly's Inside Port 25 site. You can read what I had to say about SpikeSource's WISP bundles there...

WISP+Apps Instead of LAMP or WAMP?