According to various sources Facebook (yes, the website many of us spent most of their time on) has developed a “code transformer” that promises to reduce CPU and memory usage of PHP code by transforming it into true C++ code (which can then be compiled into macine code).
Not much is know yet, however, performance estimates are a 50% less CPU load with the same amount of traffic, which would be pretty neat already.

Two things to observe is that this does not necessarily increase the performance of database operations (which itself are more often than not a bottleneck) and it does not work on some functions like “eval()” or “create_function()”.

HipHop is due to be released to the open source community soon.