The first Noel

A welcome example from Australia, in a Sydney Morning Herald interview with popular recording artiste Noel Gallagher -
You could say Noel Gallagher is all mouth and trousers - faded black ones tonight in Melbourne, worn with a dark brown pinstriped jacket. You could add he's a walking opinion who shovelled too much Colombian up his nose for a few years, a mouthy git and an egomaniac whose best years were a decade ago. He'd almost certainly agree.

It's tribute, perhaps, to the legendary no-nonsense Australian character that the phrase lives on down under. You beauties.

Tidy

From the Wenglish dictionary of Valley-speak (as spoken in the valleys of South Wales, that is, rather than the 80s Californian teenspeak. Though both Gwent and Orange County have a Newport), comes this vernacular equivalent which correctly references the original:

All jaw: All mouth, boastful, lazy, “bullshitter”. “He’s all jaw he is, all mouth and trousers, but he’s too lazy to get out of his own way.”

Seoul offence

Another couple of shameful examples of the bastardised form:
A typically ignorant example from the London Evening Standard website:
In that opening 45 minutes,Liverpool were all mouth and no trousers. For all their dominance of possession,they rarely threatened to score.

More oddly, from the South Korean Digital Chosunilbo:
The mega hit movie “The Host,” which set a new record in the Korea movie history by attracting more than 13 million audiences here, came in seventh in the first week of its release in Japan in September and fell to 10th in the second week. Park Hyun-tae, CEO of Sovik Venture Capital which specializes in film investment, said, "If the Korean movie industry is content with the current high theater occupancy rate of domestic movies here, it’ll prove all mouth and no trousers.”

Politics laid bare

Brickbats for Liberal Dem environment spokesman Chris Huhne MP, who says:
The Tories are a shambles on green taxes. George Osborne says he favours green taxes, but the special commission he set up to look at taxes did not come up with a single plan for green taxation.
This proves that the Tories are all mouth and no trousers on the environment. The voters are waking up to the fact that the Tories have no proposals for tackling climate change, merely hot air and claptrap.

and Glasgow Herald political hack Michael Settle, who writes of David Cameron:
On policy, the conclusions of the swathe of commissions are not due until next summer, leading to the charge that the Tory leader is "all mouth and no trousers".

We might allow Settle the use of the vulgarised phrase in quotes, but there's no excuse for Huhne (himself a former journalist, now MP for some suburb of Southampton on a slim majority). One trusts his linguistic sloppiness does not reflect any laxity of political rigour.