Vine Server is a free VNC server for Mac platform. It allows your Mac to be remotely controlled from any VNC viewer whether locally or on the other side of the world.
This server allows a Mac to behave like it has terminal services (like windows has).
You will not need to upgrade your mac osx leopard to lion or mountain lion to get the multiple users login.
With this software you can continue working remotely on your mac desktop, while a user sitting in front of the mac can work on his own desktop.
This is an easy way to share the expensive macs to more than one users at a time.
Multiple Desktop Servers
If there are multiple user accounts on your computer, each user can run a desktop server to access his or her user
Using Vine Server in Each User Account: Step-by-Step
1 Turn on Fast User Switching. Mac OS X fast user switching allows multiple users to be logged in to the
computer at the same time.
2 Go to System Preferences > Accounts > Login Options.
3 Select “Enable fast user switching”.
4 Start Vine Server in each user account.
5 In Connection preferences, enter a display name so you can tell your servers apart.
6 In Connection preferences, give each server a different display number (port).
7 In Startup preferences, select the “Start server when Vine Server application is launched” checkbox.
8 In the Server panel, click the Start Server button.
9 Make Vine Server a login item. In the Dock, right-click the Vine Server icon, and choose Open at Login.
You must be logged in to your user account to access it through Vine Server.
(If you cannot log in to your account in advance, see System Servers for information about logging in through Vine
Peripheral devices (such as speakers or cameras) are usually controlled by the console user (the “active” account
on the server computer).
If several users are connected and working at the same time, you might notice slower performance.