I'm sorry to drag up this long-dead thread, but was this whois information monitoring feature ever implemented (as of this post, I don't see it as an option)?? Whois information monitoring would indeed be an extremely useful feature. As a potential customer, this would help meet all the monitoring requirements I have.
Regarding @Kurian's questions:
1. Automatically monitoring important records from the authoritative name servers such as "www" and MX records when monitoring a domain
2. Checking if public DNS servers resolve the same IP addresses as the authoritative name servers, to detect propagation delays etc.
In my opinion, neither (1) nor (2) are important because the purpose of the monitor would be to detect changes in the domain's whois information itself, not to detect what DNS record values are returned for a given FQDN (that feature could be offered by the DNS monitor)