Just saw that one on the highload PHP list:
Pinba is a realtime statistics server for PHP.
It is a daemon gathering information sent by PHP processes by UDP. It is used at Badoo.
It accumulates and processes data sent over UDP by multiple PHP processes and displays statistics in a nice human-readable form of simple “reports”, also providing read-only interface to the raw data in order to make possible generation of more sophisticated reports.
With Pinba extension users also can measure particular parts of the code using timers with arbitrary tags.
Here’s a link to the Pinba manual