FCC filing. In a statement issued from the manufacturer to Kotaku, Sony said:
As mentioned when we made the product announcement for PS3, the system will have different configurations (thus, 60GB HDD with memory card slots and Wi-Fi and 20GB HDD without memory card slots or Wi-Fi both exists). Application to the FCC has been made with various possibilities in mind, however, it does not lead to a new product announcement at this time.
There is no denial of a PS3 update. I’d go so far as to say the reply even anticipates one. But it’s safe to say that the 80GB model carries no expansions beyond storage capacity. Oh well.
Sony Responds to PS3 Elite Rumor [Kotaku]