The first one is apparently called Carla, grazing on the alphabetical order, and will bring a new 8.0 browser version. Richer widgets, Dolby Surround sound support and enhanced NFC functionality are also in store with it.
Donna, apparently adds the promised dual-core support to Symbian, and rumor has it that the alleged Nokia N8 successor with the optical zoom we heard about recently, will run Donna.
Hopefully that means the N8 follow-up will be dual-core as well, and thus sport 1080p HD video recording, which, together with the optical zoom, will make it a really worthy successor.
source: Twitter via AllAboutPhones (translated)