Grenades in close combat against a dreadnought no longer require a 6 to hit them. Normal WS means grenades against dreadnoughts are going to be deadly for the dreadnought. Just a swarm of Krak grenades will do the job, as you only need to damage the poor dreadnought a couple times and it will wreck (hull points). 10 marines with Krak grenades is a pretty even match up with a dread now. MSU marines will get eaten, but larger squads like platoon infantry squads from IG with krak grenades will eat up any dread in their way.
Our Weapons are Useless
If you are locked into combat against a dread, its almost best now to not have a weapon that can hurt it. The rule "Our Weapons are Useless" allows for things like melta veteran iq squads the chance to fall back if you can run fast enough. If you get away, that dreadnought is going to get wrecked.
They now make you strike at I1, however they AP1 in 6th and S8 armour bane. They will tear up dreads in close combat. A sergeant with one is one thing.... He still has to hit, but a squad with them, is going to rip through any dreadnought they run across.
Dreadnoughts used to be dangerous in close combat, not for the damage they will inflict upon the enemy unit, but because once they did charge, they were about to lock up a valuable unit and slowly kill it. Dreadnoughts did not get any more dangerous in 6th edition, but a lot more got dangerous for them. It is now vital to know what is in that enemy unit before you just throw your close combat dreadnought into the fray.
Of course if you are a Blood Angels Dreadnought with Blood Talons, this article means much less, as they still rip apart infantry. Personally I think they should of made Dreadnoughts characters, so that they can do a precision strike in close combat.
The day of the Dreadnought is waning but not over, as the playing field just got a little bit tougher. Taking a dreadnought now is worth some extra thought to mesh into your army lists, and I think I prefer them now as armoured and mobile shooting platforms, rather than one that can get in and do some close combat damage as well.