Do you believe that encouraging children to believe in Santa Claus is wrong/lying?
I think kids should know the real meaning of Christmas. Plus they should know who to thank when they get their gifts.
to me its a personification of hope or even childhood. Its acts as a 'maker', once the child quits believing, you know him/her is maturing and you can teach them differently and have different conversations.
It's simply not being honest with your kids.
I think it's fine. I do suggest making sure they know the truth by the time they hit school or they may be in for a rude awakening.