I recived this mail from PS, so i see it as a confirmation of the hotel:
Thank you for your email.
We have noted in your registration that you will be arriving on the 26th. Please note that you will be responsible for that night and the hotel will charge you directly. You also have been assigned to Treasure Island. You will be receiving in a month or so a confirmation number.
Please do not hesitate to contact me if you have any further questions, it will be my pleasure to assist you.
Nathalie Hatter
PokerStars WSOP Event Staff
pokerstars@meridican.com