He gained three knowledges: 1) past lives, 2) karma and its
results, 3) liberation from afflictions/suffering/rebirth
See
http://balawegaya.wordpress.com/2011/04/14/what-happened-under-the-bodhi-tree/
(Partial excerpt. Buddha said:)
“When my concentrated mind was thus purified, bright,
unblemished, rid of imperfection, malleable, wieldy, steady, and
attained to imperturbability, I directed it to knowledge of the
recollection of past lives. I recollected my manifold past
lives.
“This was the first true knowledge attained by me in the first
watch of the night. Ignorance was banished and true knowledge
arose, darkness was banished and light arose, as happens in one who
abides diligent, ardent, and resolute. But such pleasant feeling
that arose in me did not invade my mind and remain.
“When my concentrated mind was thus purified, bright,
unblemished, rid of imperfection, malleable, wieldy, steady, and
attained to imperturbability, I directed it to knowledge of the
passing away and reappearance of beings. Thus with the divine eye,
which is purified and surpasses the human, I saw beings passing
away and reappearing, inferior and superior, fair and ugly,
fortunate and unfortunate, and I understood how beings pass on
according to their actions.
“This was the second true knowledge attained by me in the middle
watch of the night. Ignorance was banished and true knowledge
arose, darkness was banished and light arose, as happens in one who
abides diligent, ardent, and resolute. But such pleasant feeling
that arose in me did not invade my mind and remain.
“When my concentrated mind was thus purified, bright,
unblemished, rid of imperfection, malleable, wieldy, steady, and
attained to imperturbability, I directed it to knowledge of the
destruction of the taints. I directly knew as it actually is: ‘This
is suffering’; ‘This is the origin of suffering’; ‘This is the
cessation of suffering’; ‘This is the way leading to the cessation
of suffering’.
In the first discourses he said that he knew perfectly well
these four truths as theory, their function and fulfillment of
their function.
In the way he realized: ‘These are the taints’; ‘This is the
origin of the taints’; ‘This is the cessation of the taints’; ‘This
is the way leading to the cessation of the taints.’
“When I knew and saw thus, my mind was liberated from the taint
of sensual desire, from the taint of being, and from the taint of
ignorance. When it was liberated there came the knowledge: ‘It is
liberated.’ I directly knew: ‘Birth is destroyed, the holy life has
been lived, what had to be done has been done, there is no more
coming to any state of being.’
“This was the third true knowledge attained by me in the last
watch of the night. Ignorance was banished and true knowledge
arose, darkness was banished and light arose, as happens in one who
abides diligent, ardent, and resolute. But such pleasant feeling
that arose in me did not invade my mind and remain.”[ix]