I have read that the upcoming number combination on May 6, 2007 will be a rare event: 2:34 05 06 07.

That's 2:34 a.m. (or p.m.), 5-6-07.

There's that 234 again.  I wonder if there is significance there?

The only thing I can find about May 6 is that it is Lag Ba'Omer on the Jewish calendar, but I do not see significance.

Wikipedia says: Lag Ba'Omer is the shorthand way of saying the thirty-third day of the omer. It falls on the 33rd day of the counting of the Omer, as counted from the second day of Passover until the holiday of Shavuot. This corresponds to the 18th day of the month of Iyar.