If all it took to avoid income tax was to be paid in a different currency then I would assume someone would have noticed that by now.
Personally, I find tax returns are bad enough without including multiple currencies! :-)
AFAIK, it's ambiguous if governments consider BitCoin to be currency. I thought that's why BTC theft is problematic: as far as the law is concerned, nothing of value was taken, and at best you'd have to prosecute under hacking laws, not theft.
(I'm a BitCoin noob, tell me if I'm wrong.) :)
I'd be very surprised if that were true. BTC theft is problematic because the thieves don't get caught surely?
In the UK at least it doesn't matter if you are paid in a currency or not (i.e. "payment in kind") - you'll still have to pay tax on it.