I can't find a reliable source for this quote but it appears on several pro-2nd websites. It is highly disturbing and seems to indicate a desire to supercede state laws. But like you said I'm sure this will be fleshed out more in the McCain-Obama debates.
Obama says, "National legislation will prevent other states' flawed concealed-weapons laws from threatening the safety of Illinois residents." David Mendell, "Democratic hopefuls vary a bit on death penalty," Chicago Tribune, February 20, 2004
http://www.gunowners.org/pres08/obama.htm
Yeah, I saw that. Given the the timing of it I assume he is talking about the so-called National Law Enforcement Safety Act which was being debated in Congress right around that time (the bill passed the Senate in early March of 2004). The bill allowed former law enforcement officers to carry concealed weapons nationally notwithstanding the laws of the individual states that may prohibit concealed carry (Illinois is one such state).
It's got nothing to do with prohibiting concealed carry nationally. It has to do with the federal government overriding state laws on concealed carry, not the other way around.