Open source development is almost completely an attention economy, by contributing code, writing how-tos on blogs, or other contributions you gain status in the attention market. As one develops status, others are more likely to think of the higher status person or project. This can lead to more control over resources (as more people volunteer contributions) or more traditional job leads.
For instance one of my friends here put together a project twill: a web testing framework. As a result of his project, blogging, and conference presentations he ended up with a consulting gig.
The academic world is a different type of attention economy, it isn't nearly as automated as open-source (unsurprisingly). Here it seems to be a mix of social networking, reputation, and actual accomplishments that determine how much attention is allocated to a particular person. This reputation then translates to invitations to speak and perhaps faculty appointments (or other jobs).
For me there's a cost associated with maintaining different identities, I find it I gigantic pain to keep track of what things to place in which identities. The fewer distinct identities I have the easier it is for my poor socially challenged brain.
As a result of my thoughts about the attention economy and my own limitations I'm wondering if I should completely give up on the idea of anonymity and link all my major online identities together. (livejournal, delicious, open source development and work).