I heard through the Facebook grapevine that the Forumosa Regent Hotel is hosting Santa, and that he will let you get a picture of your children with him for a fee of $100 per picture.
Address: Grand Forumosa Regent, 1st floor, 41 Chung Shan N.Rd, Section 2, Taipei (02)2523-8000
Hours: Mon-Sun 12:00-5pm. Mon-Thur 6:30-10pm. Fri-Sun 6-10pm. Until Dec. 30, 2009
Hsinyi Area's Mitsukoshi A4 building has also put up a snow ball with Santa in it for a photo shoot.