Activehome isn't capable of it. I'm not sure if any other 3rd party software can do it or not.

But I do know that some of the higher end switches (e.g. Leviton) do have soft start (i.e. when turned on, it brightens up to 100% over 2-3 seconds) and fade off features. In addition, these also have resume dim (i.e. if you turned it off when it was 50%, it will be at 50% when you turn it on). You will definitely pay a premium for these though -- from $35 to $90 per wall switch.

Roland