At those times he didn't have the Party elite behind him, this time he does. The polling will get a lot closer before this is over. This may be the year the Chicago blacks dump the Jacksons.
Are there debates coming? I don't see any reason for Obama to debate a guy that's trailing by almost half a poll. Political conventional wisdom is that the guy behind at the start of the debate is most likely to "win" the debate (ie, gain in the next poll). Now if you're Obama why would you want to risk giving Keyes a chance of evening the race by participating in a debate? Given the poll results he can easily write off Keyes as a fringe candidate (same excuse used to keep third part guys out of debates).
Keyes doesn't have the party elite behind him now. He has the Ill GOP behind him, and the process of getting them behind him showed they are anything but elite. Then he went and criticized Cheney over his daughter, so he's not gonna get any support from national.
So far Keyes is losing about 1 point a week in the polls. He started 39% back before accepting, a couple weeks later he was 41% back, last week's poll puts him 45% back. The current trend shows the polling isn't going to get closer, though there isn't much more room to fall so the trend might reverse.
And meanwhile the great "promises" of a Keyes campaign aren't happening, he isn't keeping Obama in Illinois, he isn't helping close the gap for Bush in Illinois, and it's highly unlikely there will even be a debate much less a nationally televised debate so we aren't going to get any "true conservatism" on the national stage. The Keyes candidacy is a disaster wrapped in a faux pas wrapped in a bad idea.