This is surely just tracking nameserver records (pointing to the Go Daddy domaincontrol.com domain), the actual number of domains transferred in or out may be higher.
No, whois reports the registrar that manages the domain, the DNS is irrelevant. For example: http://whois.domaintools.com/citricsquid.com switch to "Registration" profile, "ICANN Registrar:GODADDY.COM, INC."
The one flaw with this is that it takes "up to" 7 days to transfer depending on the registrars in question. I moved a domain to godaddy 4 days ago and it still doesn't show that it's with Godaddy.
edit: Nevermind, you meant in this specific case where it's using DNS. You're right, although it can be done via the whois data.
Also, unless people are on top of it, it takes more than 5 days usually to transfer a domain. I'd imagine most people who transferred will be waiting through that window of time rather than digging for the hidden confirm quickly option.
The one flaw with this is that it takes "up to" 7 days to transfer depending on the registrars in question. I moved a domain to godaddy 4 days ago and it still doesn't show that it's with Godaddy.
edit: Nevermind, you meant in this specific case where it's using DNS. You're right, although it can be done via the whois data.