Why would they do such a thing? Well beside the fact that Hollywood is all about remakes these days, the site notes that Disney recently underwent management changes and suggests the success of a well known, similarly rocket-propelled comic book character (a.k.a Iron Man), may be the driving force for the studio in it's consideration to revisit the property.
The site also mentions that new studio chief Alan Horn may not be content with letting Marvel and Pixar keep churning out their own properties as Disney’s brand withers.
In any case, at this point there has been no indication from Disney regarding the validity of this story, or if such a project is underway, so we'll have to wait and see.
The original Rocketeer took in a mere $9.6M in it's opening weekend, and has grossed just over $46M since it's release. That's not to say it was a bad film and despite it's lackluster box office numbers it was actually well received by those interested enough to see it.
If you haven't seen The Rocketeer it starred Billy Campbell, Jennifer Connelly, Alan Arkin, Timothy Dalton and Paul Sorvino. it's set in 1938 Los Angeles and tells the story of stunt pilot Cliff Secord who discovers a jet pack that enables him to fly. His heroic deeds attract the attention of Howard Hughes and the FBI, as well as sadistic Nazi operatives.