Here is what the footnote in the New Jerusalem bible says:

"k. It is possible that this plural form implies a discussion between God and his heavenly court (the angels, see 3:5, 22); our text was thus understood by the Gk version of Ps 8:5 (quoted in Heb 2:7). Alternatively, the plural expresses the majesty and fullness of God's being; the common name for God is Hebrew is elohim, a plural form."

3:5 is: "God knows in fact that the day you eat it your eyes will be opened and you will be like gods, knowing good from evil."

and 3:22 is: "Then Yahweh God said, 'Now that the man has become like one of us in knowing good from evil, he must not be allowed to reach out his hand and pick from the tree of life too, and eat and live for ever!'"


So...I guess the angels have always been around, too? *shrug*