Note that V1 is referring to a Mac Pro, not a Macbook Pro. The Mac Pro tower has several slots for installing additional I/O cards.
I also have a one port ESATA card for my macbook pro, that plugs into the expresscard slot. OWC sells them.
Careful when buying ESATA ports... be certain you check to see if they support "port multiplier". If it doesn't say, then it doesn't support it. Without this perk, you cannot plug in an ESATA hub to hook several drives to one card. This isn't as important on a desktop where you are getting usually 2 or 4 ports on the card, but on the laptops you will get 1 or sometimes 2 ports. So if you want to be able to hook up to more than one (or two) drives at a time, you require port multiplication and the card won't allow it unless it has that feature. (it about doubles the cost too)
There are also speed differences, usually rated in gigabits/sec. 1.5, 3, and 6 gbps are common values. 1.5 will do about 170MB/sec on a drive so is good for most use. You'll need faster if you want simultaneous access to fast drives, or are hooking to a fast ESATA raid.
Like USB, ESATA is not chainable, as firewire is. It requires a hub because it's a client/host protocol, not a peer-peer protocol.