There is quite a bit of debt, but all of it is between 1% and 3% interest so it's really not important to pay it off early. They have net cash so they could pay it off completely if they wished. As Sean said, it would definitely be better to see a buyback than paying off the debt, but there are some complications to doing that based on where the money is (most is in a subsidiary right now)
I don't think that they have any debt left. But I think Caff can confirm or deny that. If you go through some of the older posts you will find many discussions about the buyback issue. In short; Nobody knows.
If I understand correctly, IMOS still carries a debt. However the company should now or close to be net debt positive, meaning the company's total debt can be paid off with cash or cash equivalent on the balance sheet.