Pet Smart kittens & cats?

I have noticed over several months that many of our American friends
are
involved in Petsmart adoption days @ Petsmart. Would I be right in
assuming
that rescue dogs & cats are available for adoption on Saturdays &
Sundays?
How does this work? Does it mean that each shelter gets the chance to
put up
their most needy for adoption, or their most easy to home animals?
Also, how
do you all feel about this? ( I remember recently that Wendy went to
pick
some up after their trip to Petsmart, this is why I am asking the
question.)

The reason that I am so interested is because over in the UK, we don't
have
anything like that. You can buy fish, guinea Pigs, hamsters, Snakes,
birds,
rabbits & occasionally chinchillas from a pet shop.......But, never
dogs, cats,
puppies, & kittens. If you want to get a cat or a dog or kittens and
puppies,
it either has to be from an adoption centre, or a layperson selling
them
through the free ads, or a breeder. I can't think of any other way you
can
get one over here. I am sure that If I am wrong, someone will correct
me.

I'm not sure if it is legal to sell a cat or kitten in a shop anymore?
Any Brits know this one?

I was wondering if we should be considering your methods of homing, &
wondered what it entails?
( adopting one from Petsmart?)
I would be most interested to know how it all works & what you think
of the
idea too?
Thanks in advance,
Sheelagh "o"