The problem with Diablo games is that the power inflation of the enemies grow too much at later stages for any viable tanking, so EVERYONE BECOMES KITER~.
If you have proper gear, though, you can tank up til early Inferno (you need insane gears). However, you will be giving up dps majorly, and you are not expected to tank in early-mid inferno.
This is just as of now, though, there is a patch coming (I think it should be applied now, as I was not able to log in last night, HK time, so I made a Monk in Asian server) and Inferno is supposed to be finished in about six months or so time from original plan. So those who have beat Inferno already are beating it non-canon style, aka MASSIVE KITING.
EDIT: Never mind about this 1.02 patch. It has not even touched Barb, or is it even that useful for any other class... I see more nerf than actual buff (though very small list), in terms of balance.
Its more of bug fixes than anything, and it does not even fix much...
EDIT2: Its not even a bug fixing patch... Its auction house search enhancer... The actual bugs related to auction house is not dealt well, and only one that is really dealt was more than 50 completed auction bug. WTF Blizzard... Set your patch priority straight...
