(It would also be interesting to know if anyone has used it as a check on radiometric dating --- for example, since we know the date that Pompeii was buried, this provides a method for testing radiometric techniques.)
Exactly that has been done with potassium/argon (or argon/argon?) dating on ash from Pompeii - and they came out correct on the date. I have the paper at home, and can look up the citation if anyone wants it.
Doc - Renne, et al., Science, v277, pp1279-1280 (1997). It should be free online if you register at www.sciencemag.org
Laser incremental heating of sanidine from the pumice deposited by the Plinian eruption of Vesuvius in 79 A.D. yielded a 40Ar/39Ar isochron age of 1925 ± 94 years ago. Close agreement with the Gregorian calendar–based age of 1918 years ago demonstrates that the 40Ar/39Ar method can be reliably extended into the temporal range of recorded history. Excess 40Ar is present in the sanidine in concentrations that would cause significant errors if ignored in dating Holocene samples.