If you want to gather some info from Dec 10 to Dec 15 2009.

You can either use 1 day before and 1 day after the desired day

svn log -r {2009-12-09}:{2009-12-16}

OR specify the date/time in this format

svn log -r {2009-12-03T00:00:00}:{2009-12-15T23:59:00}

Read more on the topic

• http://svnbook.red-bean.com/en/1.4/svn.tour.revs.specifiers.html