ip address spoofing facts or not?

i read at about ip spoofing from http://spoofer.csail.mit.edu/summary.php that it was estimated that 460 million out of 2.32 billion IP address were spoofable and a client within that network is able to spoof 16,777,215 other addresses and i was wondering how many think that the information is true if not how off do you think they are because some one had to mess up.

You can't really spoof an IP. If you were to spoof an IP, the data being sent would be sent to the spoofed IP and not your real one, thus you couldn't do anything with it.

Poison the arp table and you can do a man in the middle to capture the data Does that count