I guess it might be of benefit, plenty of other ways to get the same effect though I would have thought (hills, higher gear, headwind, backpack, cheap heavy bike instead of expensive light one!)... Although if you're a bit vertically challenged, the link below seems to suggest ankle weights may help......! Believe that s%^t and you'll believe anything.. ;)
Adding all that rotating mass to an already troublesome part of one's anatomy seems... odd.
Better would be to climb hills, ride a heavier bike, seek out headwinds, limit yourself to the smallest chainring, do interval training, ride off-road on grass, mud, sand, rise single speed, ride fixed or just ride more. In fact, I can think of any number of alternatives that would be be better.
Besides, once you take the ankle weight off (probably because you're too chaffed to wear them anymore) your cadence will be all over the place. You'd train yourself into a very lumpy pedalling technique.
This website is a good source of training and fitness information: http://www.cptips.com/index.htm
It's just one website, there are thousands out there like it, but this seems like a pretty good one to me.
There was a Belgian world champion pursuiter, back in the 60's, who's name escapes me, that was attempting to break the world hour record. He trained with lead weights on his pedals. It's a sort of pulling that weight around thing, a lot different to a heavy bike, uphill or heavy body weight. He claimed it was to simulate riding a high gear, I don't know why he didn't just go out and ride a big gear.
But the end of the story is he didn't break the record.