Nintendo has quietly registered a domain for 'supermario4.com'.
An IGN reader spotted the filing, and the site furthers the discussion by considering if it relates to the new 2D Mario adventure game Nintendo announced at its last investor's presentation earlier this year.
Outside of a release date that was to be set before April 2013, no further details were provided by the company at the time.
It's also worth noting that the Japanese version of Super Mario World was entitled Super Mario Bros. 4 as well.
Of course there's no official word as of yet from Nintendo—though they don't seem to be hiding it. The address redirects to the corporation's website and Nintendo of America is publicly listed as having control of the domain.