I think my main point was that an expert locater is more like the GAL in Outlook, but a social network is this plus interaction eg. sending messages (similar to email)

That is you use an expert locater occasionally, but you use a social network every day as it’s a read/write tool.

When you are after some help on an issue, or seeking information or a person, you can get around your vertical hierarchy, by blasting a message to your connections. Currently we save time and money from using a “back channel” in getting things done, and networks augment this in an online scenario.
Rather than waiting on your boss, to ask their boss in another office, who has to ask someone else, you can immediately be aware and connect to this person that is usually 3 degree’s or separation apart from you. I’d add to this we are reducing opportunity cost by more accurately hooking up with the best available person for the job at that time, and as a result we create new contacts and relationships.

And then there is the strength of weak ties
http://blog.hbs.edu/faculty/amcafee/index.php/faculty_amcafee_v3/the_ties_that_find/
http://www.stanford.edu/dept/soc/people/mgranovetter/documents/granstrengthweakties.pdf
http://www.annezelenka.com/2007/10/weak-ties-for-social-problem-solving-in-enterprise-20

That’s why it’s important for an expert locator to allow you to interact, ie. it enables you to find people and add them as a contact (connection/friend). This way when we visit profiles we can see who these people are connected to, and for personal reasons each person can a mass a list of their contacts.

In this respect it becomes a tool that engages an individual, it becomes your contact list, you can see other people’s contact lists, etc…And as you say, the profile points to their content like blogs, and bookmarks, where in the end you may not need to contact that person as one of their blog posts answered your query.

Now that people have some self-interest to use the tool, they are more prone to keep it updated.

You could also do searches like: show me a list of all the experts in “Excel” from within my network, or from within my network and my friends networks.

What is happening here is that Expert Locators (or even the IM buddy list idea) are becoming Social Networks, so rather than a centralised seek and find database that you use on ocassion, we have a more engaging and personally useful daily tool, where the people create the information and connections from a bottom-up approach (more self-organising), where it does most of the work itself as a collective.

People are too busy to regularly update their profile, and the employees whose expertise is perhaps most valuable (primarily the Partners) are invariably the ones with least time available to commit to such tasks, not to mention having the lowest incentive to do so.

Technology can help businesses automate this process and keep the ‘expertise directory’ up to date. ‘Expertise Location’ solutions are readily available, but few place the onus on the technology itself to automatically categorise and relevancy rank the firm’s experts in relation to a specific query. Intelligent expertise location solutions determine this based not only on the information held in HR/personnel systems, but also on the work they have done and the matters they are involved in – information housed in document management, time and billing and CRM systems. This approach frees up valuable staff time and enables businesses to collate and present all knowledge – no matter where it lives – in a community-based, easily accessible fashion.