Some new work along the southeastern tip of India shows that the Boxing Day Tsunami was rare, but not unprecedented. Now that scientists know what the erosional remnants of a global tsunami event look like when preserved on the beaches of that coast, they can use Ground Penetrating Radar (GPR) and sediment cores to look for evidence of other events correlated around the Indian Ocean basin, and use optical methods to come up with dates for them. The latest round of work has identified two previous tsunami records at 1080 years ago (+/- 60 years) and 3710 years ago (+/- 200 years). So yes those of us who witnessed this event were indeed present for an event that starts to bridge the gap between human history and the geologic record.
See: (EOS, Transactions, American Geophysical Union, Vol. 91, No. 50, 14-Dec-2010, "Subsurface Images Shed Light on Past Tsunamis in India", Rajesh Nair, Dept. of Ocean Engineering, Indian Institute of Technology)