We have been processing all COM and NET domain names using our application cluster and based on our tests we have compiled the following:

.NET TLD statistics on September 22, 2007
Registered domains: 10278275
Domains not resolving: 1212471

.COM TLD statistics on September 22, 2007
Registered domains: 73383356
Domains not resolving: 8847418

Here is the chart for your convenience.