Many players in the fan community such as Twitter had been asking for a Frozen-related party before its confirmation.
Spike Hike once tweeted that they can make a Frozen Takeover if they get enough requests. And, at one time shortly before the party was announced, he stated that it was the most asked-for party.
In an interview, Polo Field said that the team has "something planned" in response to a question asking for confirmation of Spike Hike's confirmation of the party. But he couldn't say if the team was going to go through with it.
There was a Frozen DVD package including a free 7 day Membership code and a code to unlock the Snowflake Costume found in Australia Target stores. 
Polo Field stated that the first hint about August would come in the Best Day Ever music video. As promised, Olaf, the snowman from the movie, was spotted in Puffle form in the video at the 0:46 mark of the video.
Another hint of this party to be held on August is the fact that on the 457th Issue of the Club Penguin Times in the Upcoming Events section, it says: Aug. 7 Penguin Style- Pretty cold for the summer... Check these costumes out in the Clothes Shop!
Yet another hint came in the #458th newspaper, reading "Aug. 7 - Penguin Style- Arendelle fashions hit the Clothes Shop".
The island is decorated like the fictional, Norwegian kingdom of Arendelle from the film. The Town, Plaza, and Dock is the kingdom castle and village area. The Forest has Wandering Oaken's Trading Post and Sauna. The Beach has the Valley of the Troll Rocks. Finally, the Cove and Snow Forts are based on Olaf's fantasy in the song In Summer from the film.
Polo Field explained a mechanic of the party in a sneak peek: "The team has put together something pretty cool for the Frozen Party. Members will be able to freeze all the party rooms by throwing special snowballs, and everyone can unfreeze the rooms by using the Heart emote. Awww! :)"