Marshall Kirkpatrick at ReadWriteWeb has a terrific post that includes a semantic (aka tag cloud) presentation of Obama’s inagural speech and other past Presidential inagural speeches.
Comparing the Obama and Bush speeches sparked the following thoughts:

Bush’s speech seemed to be addressed to the  world stage and had much abstract language with powerful concepts attached: freedom, liberty, America, country.

Obama’s speech is addressed to the American people and has much more change and inclusive language: keywords are people, common, change, new, spirit. 

Bush’s language was imperial (we know that that played out), Obama’s language is inspiring.