Last Friday and Saturday was when the Night Festival 2010 was on.
I was there on Saturday late night and one of the many interesting installations was this interactive artwork by Thai artist Wit Pimkanchanapong. It's called the World's Slowest SMS Billboard.
You text a message to the number and it might get displayed. Humans would put up the message!
Did I text anything? No. ;-)
Here's the short description on the Installation and how it works.