LOL Mike.  I thought that too.  Whenever my cars kick up, she always seems to be driving.  
Didn't notice it worse cornering - although its harder to hear it when on the gas.   When driving around for a while and everything is hot there as always been a faint dull thud when moving off.  It's always done it.   I did hope it might be something as innocent as a stone in the tyres but no such luck.  Also the fact that it sounds like it's coming from both wheels - would that indicate some diff issue?  It was quite warm when the wife came home last night after about 7 mile journey. 
If I take it to a garage are they going to be able to work out what it is quickly? i.e. an easy spot for a competent mechanic.
Not just replace part after part until it stops knocking?