Returning to the mentioning of the various Social Media platforms we use, LinkedIn plays a decent role after Facebook and Google Plus, though I do see great value and leverage in setting up groups for the various topics of interest we are strong in.
LinkedIn comes across as the more professional set-up and is known for a good place to promote your CV with an opportunity to get noticed in this area. The groups however look to be a strong area for us to develop in for our content distribution.
I have heard various murmurings that LinkedIn is planning more ideas that involve further interaction and news distribution, so it shall be interesting to see how it all goes and works out for the future.
So, for now 3rd on the list for value in use on the Social Media front.