(note: I am a Democrat, and I support Obama.)
Is the Obama optimism justified?
In a word, yes.
http://www.intrade.com/ does basically legalized betting on the outcomes of political processes. The idea is that the market as a whole is more accurate than any individual person, (and more accurate than polling as well,) because money is on the line. So this is a pretty good place to see the consensus view of the race.
I was looking at the numbers and here's where it stands now:
(Note, the numbers don't have to add to 100, since these are share prices, but they should be close. (inaccuracies mean inefficiencies))
So, the market seems to see a greater than 60% chance of a Democrat taking the white House, and a roughly 70% chance of Obama taking the Democratic nomination. For comparison, during the 2004 race, Kerry was never trading above Bush for any significant amount of time.
Now, the futures markets are not perfect predictors, but they are a good guide to what the informed conventional wisdom is. For someone like me who gets a lot of his information from secondary or tertiary sources (on purpose! it's filtered!), having a tap on this kind of brutally non-partisan information is pretty valuable. It helps keep me grounded.
Specifically, for this election, there are a lot of factors out there that make me optimistic, but as a scientist (more on this subject later) it's important to me that I have some kind of numerical evidence to back up my anecdote-derived hypotheses. These markets are providing that evidence.
So yes, despite having been burned in the past, I am optimistic this year.