Google Enterprise Search
google.com
google.com
2002 - "The first Google product for enterprises is released: the Google Search Appliance is a yellow box that businesses can plug into their computer network to enable search capabilities for their own documents."
Using the free versions of all three (Solr + Drupal + Alfresco), search is fast and access-controlled very easily.
I worked for a company that had a Google Search Appliance about 6 years ago, and, like others have said, it basically sat in a rack somewhere and collected dust once we started using some form of integrated search. The GSA was fast and relatively easy to use, but required an expensive initial purchase + ongoing licensing/update fees.
Not to downplay the importance of an enterprise search offering, but I don't think Google just packages there standard search in a box nor do I think 1 single GSA box can solve enterprise search.
NOTE: Despite that scathing comment, I continue work in large enterprises... sure they have their downsides, but you can also work on really cool things if you seek them out.
I'd have assumed that another HN reader was present but I'm in a city with a pretty non-existent tech community and the event only had ~30 attendees, the majority of whom were energy sector CEOs and GIS people.
For an enterprise with mixed Windows and UNIX servers and SharePoint there better options than Google. For web based data, Google does great. For mixed media that has varying security constraints we found Google lacking.
There is also a review of each one.
An interesting anecdote about the Google Search Appliance, a bunch of companies complained about them in the beginning because they conflated "search intranet" with "search file shares" and of course Page Rank is not as effective on file shares as it is on web based systems.