This came up int he panel Understanding The Complex Social Marketing Playing Field and the query that will give you the all the Google results in the last 24 hours is by adding &as_qdr=d to the end of your search query.To explain this in steps
a) Search google just like you normally do
b) in the address bar add this &as_qdr=d example http://www.google.com/search?hl=en&rlz=1C1GGLS_en-USUS292&q=barack+obama&as_qdr=d
c) You will see the results for the last 24 hours and also a drop down to change the period to 24 hours, last week, last month, last year.
Thanks Rand Fish of SEOMOZ
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