Hi, just listened to this podcast and I wanted to make a few notes about the comments made about HipHop.
1) Buildling from source: Yes, it's still a bit of a pain, largely due to the fact that we use cutting edge features not found in most linux distro prebuilt packages. In fact, Ubuntu 12.04+ is the only distro we're officially supporting at the moment since others do present a pain point in the build process.
2) Installing prebuilt packages: If you do happen to be on Ubuntu 12.04 or 12.10, you can use https://github.com/facebook/hiphop-php/wiki/Prebuilt-packages-on-ubuntu-12.04 and install will take about 3 minutes.
3) Bytecodes and VMs: HHVM's approach of compiling source was described as "very different" from PHP's. That's not entirely accurate. In fact, PHP's runtime *is* a virtual machine, and the intermediate state which HHVM runs *is* bytecode. What differs is A: What kind of bytecode is generated (e.g. dynamic zvals versus static type analysis), and where it's stored (memory versus sqlite db), and B: What happens to that bytecode when it gets used a lot (JITing).
4) Parity: One of my highest goals right now is making HipHop as close to at parity with PHP as possible. Since most of the team is working on making the runtime faster and the compiler leaner, it's nearly a one-person job, so that takes time. Extensions like redis and...I forget off hand which other was referenced... will be supported, it's just a matter of time.