Stiller, 43, directed Cruise, 46, (ensconced in a fat suit) in the recent comedy hit Tropic Thunder.  The couples bonded enough that their children are allowed to play together.

Suri Cruise is rarely seen with other little kids; so her friendship with Ella is a positive development.

Christina Taylor says that Suri makes her daughter feel like "a big girl."

"Ella used to always be the one looking up to the older girls and now she's kind of taken on that kind of big girl role."

Taylor was interviewed while attending a Museum of the Moving Image ceremony in New York to honor husband Ben, a longtime comedic actor and director.

"We've had a couple of play dates, and they're just like any other play dates," she said.

"When little kids get together, you just let them do their thing and there's no outside elements."

Yeah, hopefully no flashbulbs or shouts of "over here, Suri!" when the girls are trying to build a sandcastle.