I think I saw Blue Ivy's carseat tonight.
I was walking home from work up Hudson in Tribeca. There was this Mercedes sprinter van parked outside an apartment building. The light was on inside, I saw a car seat. A drive was aboard. Two security-ish guys were chilling rather casually in on the sidewalk. It took me half a second to realize I was in front of the building where Jay-Z has a condo (and where he and Beyonce were married) and another quarter second to conclude that that carseat must be Blue Ivy's.
I'm going to continue gather evidence to make my case airtight, but for the time being I'm going to believe I'm correct.