Neil finally has an envelope editor. This will let you visually edit pattern columns. This is very useful when you want to automate machine parameters over long stretches of time. Examples of this include changing the filter cutoff value for synthesizers to alter the tonal character of the sound or changing the granular synthesizer parameters.
After you have edited and applied the envelope by clicking the OK button, the column values will be set to follow that envelope. Later on, if you want to work on the same envelope again, the editor will attempt to reconstruct the envelope using the values in the column. However, due to the limited resolution, the result won't usually be exactly the same. This, however, should not be a big problem. The important thing is that the envelope won't be completely lost after you click OK, even though it won't be explicitly saved anywhere.
I imagine this feature will make at least my life a lot easier. It will be nice being able to automate synths without having to manually set values in patterns and then using the already existing linear interpolation feature. This will especially come in handy with the SoMono Cloud granular synth, bringing to Neil similar functionality as in AudioMulch with its' BubbleBlower contraption.