Reasons cited include the numerous domain (and sometimes search) related patents which Godaddy has been filing lately, an existing partnership between Google and Godaddy under the Google Aps for Your Domain package, and the vast amount of domain related data Google would gain and be able to potentially leverage to improve search.
The last point may have some privacy lovin' SEOs concerned....
Google is an ICANN accredited registrar since 2005, and can sell
most common TLDs such as .biz, .com, .info, .name, .net, .org, .pro.
Therefore it already has access to all the domain related data
available to Domain Registrars.
Another goody Peter, I would certainly love to have a better TOS over few domain names if Google does acquire it. Hopefully it doesn't stay as my own 5 second glimpse