Tralliance the registry in charge of the .travel domain requested permission to introduce a DNS wildcard. A DNS wildcard would redirect any traffic to non-existent .travel domains to a predetermined page. The idea is similar to VeriSign’s proposed SiteFinder Service for .com and .net domains. (SiteFinder was withdrawn after opposition from the internet community and subsequently led to the lawsuit between Verisign v. ICANN.)
Tralliance’s argument was the purpose of the program wasn’t for a PPC advertising page but for an index to ensure people didn’t think the .travel namespace was broken when people trying to guess a .travel address or mistyping a known .travel address inevitably ended up at a 404 page as .travel domains are few and far between especially when compared to a larger registry like .com
ICANN denied the proposal on technical grounds not commercial/business revenue grounds, in that the effect of wildcards are not limited to web browsing it also effect other service such as email etc.
The only other official ICANN gTLD extension with a wildcard is .museum [q235456476.museum...] takes you to their index.museum a page without advertising and helps navigate their third level domain naming structure.
Interestingly .museum has recently applied to ICANN to have their contract varied so they can suspend their wildcard system during the period of introduction of IDNs.