What do I do with my U.S. iphone plan?

I'm moving to Singapore on Monday the 26th, and I'm wondering what I should do with my iphone plan?  Will I be able to use my iphone in singapore?  Will someone there be able to unlock it for me?  should I completely cancel my plan here in the states even if I plan on coming back to visit every 6 months or so?  I figure people who have actually done it will be able to help me more than the phone company will.  Any suggestions or experiences will be most helpful! Thanks- looking forward to living there!

I'm wondering the exact same thing.  ATT said they could do a hold on your number and you just pay 10 dollars (one-time or month, I'm not sure).  But some direction on this would be nice...