We're looking to build a collaborative site for a targeted set of users (~100) based on SharePoint Services and we want to integrate social networking features such as tagging, activity streams and user profiles to encourage them to participate. This is a proof of concept and if it proves to be popular then we might consider using the technology in a new site to replace our existing enterprise portal solution (~2500 users).
We're currently looking at third party solutions such as NewsGator's Social Sites™ Enterprise. What other solutions are out there and how do they compare? What are the drawbacks to NewsGator's or other's solutions?
**Update**
We ended up using NGSS as our solution and while the product is technically sound, it's infrastructure compatibility is falsely exaggerated and their support is lacking professionalism and honesty. Our project deadline was missed and additional unforeseen software licensing and hardware procurement costs were incurred as a result. Our organization has decided that we will not be using them for any future initiatives.