This is clearly a great topic, as this question has appeared in several different iterations since Ask a Biologist started.

http://www.askabiologist.org.uk/punbb/v … php?id=313

I am not going to go into any of the information for and against the possibility that we might or might not be able to do this one day, rather I wish to pose a more philosophical question, based on Dave Hone's response at #5.
This relates to having animals in captivity.  Having a 'caged' compsognathus, would tell us an inordinate amount about the physiology of that particular animal, but would we still get the essential 'dinosaurness' as well?  This is the same for tigers and bears, elephants and hippos.  Having an individual in a cage may mean that we preserve the 'genome' and the physical organism, but does it give us the individual.  I am not trying tosay that zoos canot support biodiversity, because they can.  However, bringing back an extinct animal that will be an exhibit, however much it will raise interest in science, is not necessarily the best thing for the animal.  Unless we set aside enough land (say a small island near Costa Rica, Isla Sorna say) I think it would be wrong (even were it to be possible) to bring back an extinct animal.  I have caveats that might make it 'OK', but I would essentially say that extinction happens, and we have to be humane in the science that we do.  Does that make sense?

But of course, since cloning dinosaurs isn't much of an option right now, a sensible scientist would use other methods to try and answer such hypotheses - through phylogeny, through biomechanics, or whatever.

Leaving aside all the enormous practical difficulties that mean we will almost certainly never be able to do this, having live dinosaurs would of course totally revolutionise dinosaur palaeontology.  We would no longer have to argue about, for example, how much the bones limited neck movement -- we could just watch them and see what they do.