Depends on how/when you're getting/spending your electricity. If you're just running your mining operation out of your home, during daylight hours then you'd probably be about right. Presumably mining successfully has a lot to do with getting your electricity at a steep discount. The way we generate electricity, that's entirely possible at certain times.

We're not going to stay in that relatively narrow band for long though, with the growth of this thing. There's only so much "spare" on the grid, off-peak, and this whole thing relies on wasteful means of energy production, storage and transmission.

So on one hand (hopefully) the opportunity to scavenge for cheap CPU cycles is going to contract, while the market for bitcoin expands? Yikes.

That is correct on order of magnitude, at least (25 pounds ~ $33 today). That's one of the reasons Steam is no longer accepting bitcoins[0]:

  > transaction fees that are charged to the customer by the Bitcoin network have skyrocketed this year, 
    topping out at close to $20 a transaction last week (compared to roughly $0.20 when we initially enabled Bitcoin).

[0] http://steamcommunity.com/games/593110/announcements/detail/...

Big miners are likely using somewhat cheaper electricity than that, but yeah, the cost of a transaction could well be in that range. The cost of a transaction to a bitcoin _user_ is now significant.

In parts of the former USSR, energy costs 1/8 or less of the price in the developed world.

About right. The block reward more than pays for it.