According to Kevin Murphy (pointer from Bret Fausett), Verisign is internally testing a mechanism that would return resource records in response to queries for non-existing domain names; if the query comes from a web browser, the effect would be that users are redirected to a web page that presents existing sites to them.
Users and developers are deprived of the ability to choose themselves how to deal with such a situation -- by choosing web browsers that do smart things about non-existing domain names, by configuring their web browser to feed the bad address into their favorite search engine, or by just fixing their typo.
If the query does not come from a web browser, the behaviour described just means returning wrong error diagnostics, and creating another problem to route around.
What Verisign is testing here (and Neustar has "tested" in May, in a live registry) is a fundamental breach of the Internet's most fundamental design principle. And it certainly won't improve users' surfing experience.
If Verisign was actually striving to improve user experience, then it would not overload existing query types with new and bad semantics, but would suggest a new "fuzzy" DNS query type to which a name server can respond with records that point to possibly corrected query strings -- if the user's browser chooses to ask for them.