overnight walk

Hi, everyone.  The first weekend in June I will be particpating in the 'Out of Darkness Overnight Walk' in support of suicide prevention and education.  In essence, it helps to bring the stigma of suicide and mental illness out of the darkness.  The walk starts at dusk in New York City, and ends around dawn, for approximatley 18 miles.  So, I have a couple of questions.   Anyone else out there planning on participating in this walk?  And, have you ever done a long distance walk like this?  If so, I would appreciate any tips you might have.  I currently run 3+ times per week (30-40 minutes), yoga twice a week, and strength training 3 times per week.  Thanks for your input! 
http://www.theovernight.org/index.cfm?fuseaction=home.viewPa ge&page_id=742C7D2A-FEAB-2DA6-FE0972E0264CC80E     -margaret

 its sounds interesting.  This is the first I heard of it.  If I can get a few folks from my church interested I might come down for it.  Thanks for posting the link.  

I've never done a walk like this, but have done a marathon, but that was during daylight :)

That would be great!  Let me know if you do...  :)  -margaret