Expression of congratulations or approval. The precise U.S. equivalent is Good for, as in Good for you!, Good for him!, Good for us!, etc. It’s an Australianism and (in the manner to No worries and kerfuffle) appears to have been taken up first by the Brits and then by the Yanks. The ur-form is Good on ya, mate!
Another scene, the Elton John party, held in Taj Mahal-size tents outside Pacific Design Center off Melrose. Ever the pessimists, we gird ourselves for letdown. It’s the 16th year Sir Elton has done this, and good on him. (William Booth and Hank Stuever, Washington Post, February 26, 2008)/We all contain multitudes, so if Mr.[Anderson] Cooper — who likes to work all the time and has another job on the side doing occasional stories for “60 Minutes”— wanted to take on another assignment, good on him. (David Carr, New York Times, November 7, 2011)
notoneoffbritishisms.com 
1. “Good on” (Australian)…what is the derivation? Could this be an Aussie-originated extension of the common usage elsewhere, as in “That looks good on you”? Or does this usage have some other source?
2. Generally, with the world getting ever smaller via modern devices and instant communications, one might expect to see and hear more rapid idiomatic interchange, and even worldwide adoption, of local terminology. An off-shoot of this could be ever-reduced selection of “over the top” by respondents to the polls associated with these blog entries.
Hal, the first cite in the OED is from a (presumably) Australian 1914 novel called “Simple Simon”: “‘What ho!’ she exclaimed. ‘You’ve biffed him. Good on you, my lad!’” I do not know what “biffed” means. “Good for you” predates it, for example, in Louisa May Alcott’s 1874 “Old-Fashioned Girl”: “Good for you, Polly!”
If you hit someone you biff them, in the UK at least. We borrowed this from the Australians, as we borrowed “Go [name]!” from you guys. And “you guys”.
“Good on you” was used for “good for you” on (Anglophile) Joss Whedon’s TV show “Buffy the Vampire Slayer” in 2002’s “Same Time, Same Place” (American character) and “Angel” in 2003’s “Life of the Party” (British character).
Since “wait on” for “wait for” is American Southern (I’ve been waitin on y’all for half an hour), I had assumed “good on you” was as well.
I have also a sense that “Good on you!” is in American Southern usage. To me it has a subtle distinction versus “Good for you,” to wit:
“I found a large bag of money!” – “Good for you!”
“I found the owner and returned it!” – “Good on you!”
Theres a further extension to that which is “good on you mate” or “good on ya mate” which is distinctively australian.
Reminds me of something amusing I read a few years back:
“The Los Angeles Times published this correction in July: “In Monday’s Morning Briefing column in Sports, Australian swimmer Leisel Jones was quoted as saying ‘Good honour’, referring to former swimmer Amanda Beard’s appearing in a Playboy pictorial. In fact, Jones said ‘Good on her’.””
The Australian usage for these words depends very strongly on the tone used. Sarcastic usage seems more common (to me) these days.
eg. You forgot the $20 you owe me? Again? Yeah, good on ya…
We have encountered “Good on you” in British Columbia, too. No surprise, eh?