According to the nice folk at the US Navy Observatory, today, June 20, 2008 at 23:59 UT will be the Summer Solstice.
To most North Americans, this is the day we mark as the start of Summer. When I was in Ireland, May 1st was the first day of Summer and today would be considered the high point of Summer. Where ever you are north of the equator and whenever you start your Summer, Happy Longest Day of the Year!
Enjoy it as you will. I will be driving to Lake Tahoe for CampCamp 5.0. I should be on the Interstate 5 driving north at 4:59pm Pacific Daylight Time.