A recently released series of fan questions posted by Eidos on the Hitman Forum website seems to indicate that the game has been completed, ensuring it will meet it's announced release date of May 26.

Q: How do you feel about working on such a great game like hitman, and how do you feel when you are done with the game?

A: It has been fantastic working on Hitman Blood Money. It has also been very tough. There have been many nights and weekends, where we've been working on the game, but all of the people at IoI are fantastic, and so it feels more like having fun than work at times.
I'm writing this, the day after the PC version has gone goldmaster, and shipped to the manufacturer, and I have to tell you it's a wonderful feeling.