I finally made peace with the fact that although the summit was conveniently located in my home city (this time), if it was in another city, birthday or not, I would have missed the festivities. Instead I focused on the reality that Prince did not know exactly which "day" of the week was his birthday -- so we sang happy birthday the night before then celebrated in fine style at his party the following Saturday.
Sometimes being a working mom means you will miss precious moments. But increasingly, I am realizing that the key to my sanity is making choices that are practical with the understanding that I cannot be everywhere, all the time and I will never make everyone in my life happy. So if my son is too young to realize that we celebrate his birthday on a day that isn't his birthday, then the world won't stop if I "miss" his birthday... especially if I make up for it by giving him personal neighborhood train rides at his party :-)