yep, exactly if any bid is placed during the last
5 minutes and the seller has that option enabled
for the auction (most sellers have it) then the
auction is extended 5 minutes more.

What do i think about it? Well, it's obvious that
the seller has more chances of getting a better
price for the item with this feature, so it's good
for the seller and bad for the buyer. Anyway,
watching it from a neutral point this way is much
more fair than ebay as it's more like a real live
auction. With this feature the bidder who is
willing to pay more gets the item without having
to worry about being snipped. In ebay everybody
ussually waits for the last seconds to place the
bid so the person who entered the highest bid wins
even there might be other people who would have
wanted to go higher and thought that the bid they
were placing was enough to get the auction.

Anyway, the yahoo system also has some flaws, as
people is able to be raising little by little the
auction's price and also in some situations even
know if they are tied with the winning bidder
(they know that if they raise a little more they
win). What i really hate of yahoo system is that
for example if you place a maximum bid of 10000
yens and the current price is 1000 yens during the
5 last minutes someone can keep raising the
auction by 100-500 yens and this way autoextending
the auction forever.

If i had to design a more fair way to handle
auctions avoiding snipers i would do it like these
rules:
1- During the last hour (or 2 hours, exact time to
be determined) only the bidders that have already
placed a bid are allowed to place more bids on the
item. - (This way we can get rid of many snippers)
2- During that time, if you place a bid you are
not allowed to place another bid for the next 7-10
minutes - (this will make bidders think carefully
before placing a bid and not trying to raise the
auction's price little by little)
3- If a bid is placed during the last minute the
auction is extended for 5 minutes. - (this would
prevent last second snippers as if they place a
bid on the last second the auction is extended 5
minutes and they probably won't have a chance to
place another bid before the auction is over)