It is still there. If you vote within the first 30 minutes you will share part of your curation rewards with the author.
To simplify it - if you found an amazing post that didn't have anyone voting for it, and you voted for it right at the 30 minute mark, then after that a ton more people found it and voted on it and it made it to the trending page - you would get a large amount of curation rewards.
These should help :)