Alastair Reynolds
I'd highly recommend Reynolds as a new (post-2000) sci-fi author. His work is mostly space opera scale set in (what I'm about to make up as a term) the semi-far future - far enough for common space flight, colonisation of other galaxies, and some diversity of human augmentation, but not much in the way of 'proper aliens' (which makes meeting them all the more interesting when they do appear).

I'd probably start with Chasm City, which is set in 'Revelation Space' (the name of the first book and the de facto name for that universe) - while the rest of the RS novels should be read in order, that one is self-contained and very well imagined. A film noir thriller with three cleverly interwoven threads and a delightfully rich sci-fi setting.

If space opera is your thing, I'd echo the recommendations above for Iain M. Banks and Peter F. Hamilton, and add Dan Simmons to the list.

If space opera isn't your thing, have a look at China Mieville. Described as 'weird fiction', from what I've read of his output so far it's real world settings with odd or sci-fi elements. The City and The City was most enjoyable.
(annexed, Mon 9 Jan 2012, 12:58, 1 reply)

Perdido Street Station by China Mieville is very good as well
IMHO, innit
(square go, Mon 9 Jan 2012, 19:02, closed)