From my experience, the release cycle of iSilo looks like this:
V4.x b1: major release update with new features
V4.x b2:
V4.x bx: b2...bx contain fixes for the new features - but no additionally new features are added until final is out
This is why you don't see any other new features in iSilo V4.0 Final other than those that were introduced in V4.0 Beta 1. Now, that iSilo V4.0 is final, you can expect the next beta to contain new, yet unseen features.
Hope I made this somewhat clear
