It is pretty much silly nonsense. For one, the orbiter vehicle is not designed for the thermal environment of interplanetary space (in the middle of nowhere you are not shadowed by the Earth for half the time). I'm also skeptical of the ability of the orbiter vehicle to withstand such a long time spent in space, regardless of whatever 'stuff' you bolt onto it... Soyuz for example has a limited "shelf-life" docked to the space station.
Secondly landing a shuttle on Mars would probably be impossible without major alterations; even with a large deployable parafoil, you have problems... you certainly cannot land on the wings, they are far too small to provide effective lift.
A shuttle also weighs around 110 tons. Add another 15 tons for spacehab and other equipment, and you get 250 tons. Add maybe 35-40 tons for the connector truss (based on the ITS of the ISS; it is not specified how long the truss connecting the two shuttles would have to be, but it is certain that to provide considerable artificial gravity it would have to be quite long and also sturdy- connecting two 125 ton masses together is no easy feat. Of course, such a truss would probably be quite heavy) and you get nearly 300 tons of mass... I cannot think of any existing rocket stage that could propel that amount of mass, if you could somehow get an S-II (!) into orbit all by itself, you could potentially propel the stack to Mars on a hohmann trajectory (I forgot the actual value, so I may be wrong), but this is also disregarding docking systems and on-orbit propellant storage systems.
And of course, there is one more, tiny problem: You lack a return capability entirely.
Sending people to their deaths is not an achievement, not scientifically, technologically, or politically.
EDIT:
Mr. Butakov's suggestion sounds like a joke. For one, this paragraph is completely unreadable:
"I propose to consider the use of the shuttle in space (flight to the moon, the delivery to the lunar station equipment used ISS), return it to Earth. I believe that for a lunar launch enough vertical separation, or at an angle,"
However since this was translated from Russian, it might be the fault of the translator and not the originator... here is the Russian text, maybe someone can offer a better translation:
"Предлагаю рассмотреть вопрос по использованию шаттла в космосе (полеты на Луну, доставка на лунную станцию использованного оборудования МКС), не возвращать его на Землю. Полагаю, что для лунного старта достаточно вертикального отрыва или под углом"
I really wonder what this guy's claim to fame (other than suggesting the use of space shuttles as cislunar vehicles) is... I mean, if this guy can do it, maybe I can approach CNN or NASA with my 'space flight concepts'... what a pity that they would either kill their astronauts or technicians, or both. Maybe they'll kill me as well.
