At the top of app_main, before I do much of anything, I have about 167KB of internal RAM. When I'm done creating my objects (I'm using C++) I have about 152KB. As I mentioned before, each task takes about 8KB, except when my Wifi task (not to be confused with the system wifi task) starts making calls, it eats up a lot more.
I could look through my code for things that could be allocated const, but I don't think there are enough to make much difference. Your comment about the static/dynamic wifi buffers is interesting; I look forward to seeing what Angus (or anyone else) has to say about this.
As a side note, I wonder whether anyone has any numbers on how much more space v4.1 and NETIF take up than their predecessors.