Leap seconds are expected to become more frequent, and the last decade has had unusually few leap seconds.
Does that mean we expect there to be more than a couple of leap seconds every year? (Based on the "more than an hour over 500 years" statement)
Err, yes, that does sound an order of magnitude out, now I come to think of it.
The original proposal allows updates four times a year, though only the July and December updates have been used.
Four times a year, with up to two seconds added each time should put an upper bound for adjustments accumulated over 500 years to:
500 years * 4 updates/year * 2 seconds/update = 4000 seconds = 66 2/3 minutes
So an hour in 500 years seems to require adjusting almost as much as we can, which isn't realistic.
Is this really true? Based on http://en.wikipedia.org/wiki/Leap_second
It seems like there's only been 25 leap seconds in 40 years. That's around a minute every century..