VSP is Voluntary Separation Plan. It's different than early retirement, because it's not just to get people to retire early. Typically there's some target criteria, like having a particular rating on your review for the past N reviews. Not everyone will take VSP -- they're assuming a certain percentage of people offered will. There's also limits for groups to prevent a mass exodus from one division.

I know a few people who were offered VSP previously, but they're still at the company so it's not like "If you don't take VSP you're going to be fired soon."