@ David A, i agree this is an opportunity for google to take yet another shot at 'social'.
@ Diego, i'm a MS Office 365, Outlook, Google apps for Business, Mac user... old habits die hard. Certainly security is always an issue, especially when it comes to sensitive company data or my personal financial data. Encryption is always nice. These days it's hard to transact with the rest of the world without your data sitting on someone's servers. Business still gets done person to person. I think LinkedIn could do a much better job of helping employees and employers leverage that, but LinkedIn was born in the recruiter world and those habits also die hard.