Scribe is a server for aggregating log data streamed in real time from a large number of servers. It is designed to be scalable, extensible without client-side modification, and robust to failure of the network or any specific machine. Scribe was developed at Facebook and released as open source.
Scribe is a project hosted at SourceForge.
http://sourceforge.net/projects/scribeserver/
Scribe is implemented as a thrift service using the non-blocking C++ server. The installation at Facebook runs on thousands of machines and reliably delivers tens of billions of messages a day. If you use the site, you've used Scribe.