A little late to chime in here, but I've been working on my own PHP syntax highlighting library. It is still in its early stages, but I am using it for all code samples on my blog.
Just checked out Hyperlight. It looks pretty cool, but it is doing some pretty crazy stuff. Nested loops, processing line by line, etc. The core class is over 1000 lines of code.
If you are interested in something simple and lightweight check out Nijikodo:
http://www.craigiam.com/nijikodo
