If the recession was postponed until after the election, or the bottom simply never fell out (Paulson took more decisive action) then you're going to have a third straight nail-bitter. If the election happened on September 14th, here's what the results would look like according to the polls:
Obama/Biden (D): 49%, 273 Evs
McCain/Palin (R): 49%, 265 Evs
Other: 1.5%
Keep in mind that McCain was trending up in the polls following the Republican National Convention. It would have been very conceivable for McCain to win the popular vote and lose the electoral vote, or visa versa. If the map above was accurate, the results would be the closest in Colorado and Michigan for Obama, and in Virginia and Nevada for McCain. Wisconsin should be at 50% for Obama, my bad.
So you wouldn't have the election decided until a day or two later, though I figure both candidates would have been willing to concede rather than push for a recount. The pundits probably would have said that Obama won the election due to young people and Latinos in the Southwest (holding McCain under 50% in Arizona), but nearly lost it due to the white working class breaking hard for McCain (case in point Michigan, Ohio, and Pennsylvania).
Going forward, Obama probably keeps Paulson on as Treasury Secretary due to keeping the economy out of a serious recession. In the Senate elections, the Democrats pick up five seats (AK, CO, NH, NM, VA), while losing close races in MN, OR, and NC. The Democrats also make modest gains in the House. This might actually benefit Obama, as the economy is less of a concern and he can focus his efforts on domestic and foreign policy. He probably gets less accomplished, but there is probably no Tea Party or massive 2010 wave election.