This is, as you might expect, a continuing source of discussion on the ebay forums. In response, a number of the folks who hang out there, including myself, have put together web pages that discuss the topic in some detail in order to keep from rehashing the same arguments over and over. Mine is here: http://www.moyen.org/snipe

The main issue with extending the auction by a few minutes after the last bid is that, in order to eliminate the "problem" of last-second bidders, you've made everybody into a last-second bidder. And if you're not available at the end of the auction (due to time zone differences), too bad for you.