There's been a lot of "much to do" regarding the Verisign "typosquatting" service. Not least of which is what this will do for applications that use the DNS to check whether or not a domain exists ("checking availability" in industry parlance). Verisign has apparently made accomodations for application developers that have this need - get accredited and use RRP.
"It has come to our attention that some registrars and/or some large wholesale domain name purchasers may be conducting name availability checks by doing DNS queries against the VeriSign g-TLD servers. Conducting queries in this manner is not an accurate method for determining name availability, as the zone file does not reflect the complete listing of registered domain names. In addition to this method being flawed, it will now yield inconclusive results as nonexistent domain queries will return our Site Finder response page. Therefore, Registrars need to use the RRP CHECK command when conducting domain name availability searches. Registrars should also contact their reseller partners and ensure they are aware of this as well."

[- 09/15/2003 VGRS Bulletin to Accredited Registrars]

I find it amazing that registries would, one month, make an appeal to application developers and ISPs for broader cooperation and support and the next, completely slay them with something like this. The level of apathy regarding the "filtering problem" and the level of cynicism surrounding this launch is completely understandable.

I'll take "Things that break the 'net for $500 Alex."

Last thought - I wonder if Klensin is going to update "User Interface Evaluation and Filtering of Internet Addresses and Locators -or- Syntaxes for Common Namespaces" (whew!) to take into account this type of "best guessing"?