The Party Plot has all of the necessary things to host a party. Many things can be found on the plot and sometimes events are hosted there by the Helpers.
There aren't regular events at the Party Plot but some Parties are sometimes hosted. If there isn't a private event on, the plot isn't put on denyall usually, which means it is accessible at any time, you can host your own parties there but be aware that you wont be able to build or play music on the plot without a Helper. You can also not interact with any block.