In Singapore, according to this Ministry of Education Web page, we celebrate International Friendship on the third working Friday of term 2, which is this Friday for 2007. It might be interesting to note how the content on the page seems to have been written for local teachers, and that the observation of the occasion comes under the ambit of National Education. Update – May 4, 2007: The NE site has moved, so the new page for IFD is here instead. The new page is more appealing visually and seems to have fewer words.
Internationally, International Friendship Day appears to be more commonly celebrated on the first Sunday of August ‘in several countries’, according to this Wikipedia stub. (See this page, for instance, and notice how it is interpreted quite differently in Australia.) I suppose if we were to do the same, it would clash with National Day. And we already have Friendship Day, which is a ‘euphemism’ for Valentine’s Day.