Android will be using ext4 starting with Gingerbread

Theodore Ts’o reports that …

Starting with Gingerbread, newer Android phones (starting with the Nexus S) will be using the ext4 file system.

Android Arena mentions one of the main advantages:

YAFFS is single-threaded, which would have been a bottleneck when trying to record those full HD video clips, and save them to the flash memory, whereas Ext4 doesn’t have this limitation. Thus the new file system is more suited for usage with the multicore ARM-based chipsets that will be creeping into handsets and tablets next year. Ext4 will actually improve the handling of data loss, if developers make sure their application data is getting to persistent storage on time.

I am wondering what happens to existing mobiles which upgrade to Gingerbread? I would probably need to backup all data and format the card as ext4 myself.