[ODE] get acceleration?

[jon at shovemedia.com]

is there a built-in way to get at the acceleration on a body?
or am i going to have to sniff the linear velocity every frame
and compute it myself?

i'm working with a system which sends position data to client
machines every 20th step or so. what i want to do is send an
"extra" message for any collision which causes the acceleration
to change beyond a certain threshold. thoughts?

:j