There are lots of opinions and answers to this question.  For starters, here’s a lively blog post, responding to this editorial last April.  Consider also this blog post.

What do you think are the barriers to data sharing?

Data from: Thompson S, Daniels K. 2010. A porous convection model for small-scale grass patterns. American Naturalist 175: E10-E15. Dryad Digital Repository. http://hdl.handle.net/10255/dryad.857