The origin of the name 'Ivy' is pretty cool. Other than that, Blue is silly. Well, since they had a girl it's silly. If they had a boy, that would be sick, Jay could be like "Blue, you're my boy!". Although, I'm pretty sure so many youths will be naming their children 'Blue' now and by 2013, it will be atop the baby name list for both genders. Eeeesh.
She'll probably go down as one of the most talented people in the history of everything.
Possible name meaning:
Also, Beyonce being born September 4th, Shawn Carter being born on December 4th (Jay-Z was born at a later date, Late 80s, I believe) they married on April 4th. Seriously, the 'Ivy' thing is pretty cool, I think.