A new Census Bureau report was just released that gives a highly detailed look at turnout during last year's campaign (summary press release here and coverage here). The main takeaway is that 2008 actually saw a decrease in turnout among eligible voters (those 18 and over). The main reason for this decrease, apparently, is that older white voters decided to stay home in significant numbers.
While turnout among the young increased, it was the only age group whose numbers were up significantly compared to 2004. Largely responsible for this spike, it seems, is much higher participation by young African-American voters whose turnout increased 8% over 2004 and gave them a higher turnout rate than young whites. Overall, though, younger voters still had the lowest turnout rate. Thus, the longstanding correlation between turnout and age was maintained.
While I haven't dug through all of the date in this report yet, it seems further indication that although the 2008 election brought many new voters into the political process, it didn't produce an electorate that was radically different from what we've seen in recent contests.