Dunno if this has any direct relevance to Earth's orbit or magnetic field, but the stuff swirling around under our feet appears to be getting more active. Yellowstone National Park is one big caldera, a 'supervolcano' and it is getting more active in the Last few years.
http://www.bbc.co.uk/science/horizon...olcanoes.shtml
And btw, after some Googling I think the issue is rotational speed, not orbital speed. I couldn't find anything about earth's orbit changing, and I don't think we can measure that accurately enough to notice 1 second's difference. But I did find articles about changes in Earth's rotation and how they have oddly noticed that some years they need a 'leap second' and other years they don't.
http://en2.wikipedia.org/wiki/Leap_second
http://www.astronomy.com/Content/Dyn...1/617efgfc.asp
http://www.astronomy.com/Content/Dyn...1/617efgfc.asp