Software Version Checks Extension for Burp Suite
This Burp Suite plugin passively detects server software version numbers, even during scanning, spidering, etc. It is written completely in Java and takes advantage of the Burp 1.5.x Extender API.
Often the server version is revealed only on error responses, which may not be visible during the normal course of testing. Some examples are:
I'd be interested in any feedback, please tweet me: @codemagi
Burp Suite 1.5.x required for use.