Yes, it means ready, willing and capable.

Not ready, exactly, so much as interested, or able. "Are you up for drinks after work [or would you rather not]?" "She wanted to come but she wasn't up to so much walking." "i'm not up to having this conversation now. Ask me after I've gotten some sleep."

It doesn't really mean ready. It means: are you interested? Are you willing? Would you like to do this thing? And also, are you in the physical and mental shape to do it?