Sorry to be the bearer of bad news, but they have been promising the heating stuff will be 'soon' for well over a year (I'm waiting for it as well) so unless there's been something new on it that I haven't seen yet, I wouldn't expect anything in the near future.
There has been an update last month showing model numbers and images of the kit, so im assuming its nearer than it has been in the past.
I'll be using a shower extractor inline fan to vent out of the cupboard back into the house in the stairwell as i dont have any heating there so this will help and it wont be wasted energy.Great thread, just wondering is there any ventilation in your AV cupboard if so what do you have?