We’ve just published ArtFlow v1.1.12 – this version contains lots of bugfixes and palm rejection.
Few important notes about palm rejection: it relies on data provided by device and this data varies widely between devices. It was mainly designed for devices with active digitizer (Note, ThinkPad) but works with touch only input (Nexus 7).
Still on some devices (eg. Transformer series has built in palm rejection, Nexus 10 filters palm touches and returns them as normal touch points) it doesn’t work, in some cases enabling palm rejection on touch only device could lead to filtering out all touches (I don’t know any device that behaves that way but with almost 500 of them I really cannot be certain) – there is safe mode for this, holding back key will disable palm rejection.