i'm always torn about this sort of thing. its clearly a case of adopting common and (previously?) incorrect usage because it has become popular - this is characteristic of many differences between 'us' and 'uk' english.
i'm partly torn because it seems fruitless in this particular case. losing the of is surely an optimisation, but i struggle to see the difference in intent. despite the examples by others in comments and such they all work equally well by using the 'correct' grammar including 'of'.
if this does take off i'm sure it will be recommended against heavily in style guides. i recently opened up a copy of that 'famous' ap style book - the defacto style guide for the us press - and was shocked to see how much of the content about grammar and punctuation is stuff that my generation of brits were taught as 'the rules' from quite an early age. again, i'm not really sure if its good or bad...
on the one hand its not hard to just learn the rules and use them... on the other its more convenient to be lazy. the advantage of the latter is ease of use, but the advantage of the former is consistency and clarity. since we write and speak for other people i am inclined to lean towards the former... but when mistakes are common enough that argument is void and i'm inclined to think the other way.
its certainly an interesting area to say the least... i just hope it never gets so far that 'there' is accepted as an alternate spelling for 'their' or 'they're'. :)