From the BBC News website:
There is a giant black hole at the centre of our galaxy, a study has confirmed.
German astronomers tracked the movement of 28 stars circling the centre of the Milky Way, using the European Southern Observatory in Chile.
The black hole is four million times heavier than our Sun, according to the paper in The Astrophysical Journal.
You can read more on the BBC site (I cant find any other links about it yet)