Unfortunately since Verisign owns the tld they can do whatever the hell they want....the only way to block it is to have your ISP enter their IP for that search page to prevent it....
.us and .info tld owners have always done this
what they are doing is redirecting all non-owned domain names to their page...unfortunately for them they cant handle the traffic which is why you see it intermittently
also think about the real benefit they will get from this....as of right now they arent getting any perclick pay for it...but they are getting good stats on which mistypes to buy and post for profit
looks like they are using some form of a combination of alltheweb and looksmart results for their searches so if you rank well on those, you will actually get a little benefit boost
but gotta agree.....it sucks, but it is an easy way to find out if there is a misspell domain for sale LOL