Public Collaboration vs. Secrecy

On the AVC blog there's an interesting discussion in the comments of this post about the merits of open information sharing versus the competitive advantages of secrecy.  To put this in context the author of the AVC blog runs a venture capital firm that's portfolio is concentrated on what most would call "Web 2.0" companies, so a lot of the businesses he invests in thrive on the open flow of information.  That said, the comments contain a nice discussion of the various considerations of the balance between open information sharing and secrecy.

My favorite comment pointed to a case about Lego asking for suggestions from their user community, a Lego fan blog putting out that call, fan's submitting suggestions via comment on the blog and then Lego asking them to use a form on their site to submit suggestions so that competitors couldn't steal the ideas.  Lego's stance is understandable, but an interesting follow up question is this: Let's say that Lego's fans preferred, strongly, to post suggestions to their favorite fan blog so that they could have discussions with other fans and maybe even collaborate on and improve their ideas.  Is it more beneficial for Lego to risk competitors seeing the ideas in return for getting more and potentially better suggestions via fan collaboration, or is it preferable for fans/customers to submit ideas in isolation even if it means fewer, potentially weaker suggestions?