An alternative package is RJSONIO. To convert a nested list, lapply can help:
l <- fromJSON('[{"winner":"68694999", "votes":[
{"ts":"Thu Mar 25 03:13:01 UTC 2010", "user":{"name":"Lamur","user_id":"68694999"}},
{"ts":"Thu Mar 25 03:13:08 UTC 2010", "user":{"name":"Lamur","user_id":"68694999"}}],
"lastVote":{"timestamp":1269486788526,"user":
{"name":"Lamur","user_id":"68694999"}},"startPrice":0}]'
)
m <- lapply(
l[[1]]$votes,
function(x) c(x$user['name'], x$user['user_id'], x['ts'])
)
m <- do.call(rbind, m)
gives information on the votes in your example.