It's the bane of the network admin: finding the most elegant way of keeping all of a user's files accessible from any machine on a network. Vista actually has a pretty decent solution in its Sync Center.
Access to a shared common location on PCs helps, but other than setting up network shares on the local machine and using third party software, there's no easy way of achieving the desired result. (Of course, one solution is a dedicated file server, but it's not always practical from a cost or administration perspective.).
The Sync Center in Vista aims to provide a solution, enabling users to set up sync relationships between different Vista-based machines (Vista only, unfortunately). It's an extension of the old Offline Files technology and the Windows XP Sync Powertoy.
To set up a sync partnerships, go to Start, All Programs, Accessories, Sync Center. The first screen displays your current partnerships and the status of each of them. Click on "Set up new sync partnership". Highlight "PC-to-PC Sync" and click Setup. You are then given a checklist of prerequisites - the computer you want to sync with must be running Vista, have PC-to-PC sync enabled, must be on the same network (not sure whether that means the same logical network or actually on the same subnet), and that it must have a user account/password which are exactly the same as the one you're currently logged on with. Interesting, as this suggests that sync partnerships are only kept up to date with a user logged on, rather than just having the machine powered on.
From what I discovered, it looks like to set up a sync partnership you have to be using a user account with a password - blank password accounts don't authenticate properly.
Click Next and PC-to-PC sync is enabled (and you get one of those highly annoying authorisation requests). The next screen prompts you for which folders you want to share. Note that you can't add any custom folders - hopefully this will change in the final build. The options available are all user-specific folders - Documents, Contacts and so on. You can only choose one folder - no multiple selections. Click Next and you're prompted for the name of the computer you want to sync with. If you've already synced with the target computer before, it should be in the list. Otherwise you need to know the target hostname - type it in and click Add then OK.
Once done, you have a sync relationship which will stay active for as long as you're logged in. Each sync is kicked off manually, but you can create a schedule to keep it humming regularly.
Sync Center is still rather buggy, with the inability to sync multiple folders or custom folders and syncs taking a loooooong time, but the basic layout is there. For home users with multiple PCs, it's going to be a pretty sweet application if it ends up working the way it's supposed to. In the workplace it's far less useful - most people only have one PC and access files on a network. Admins will want to make sure that people don't use sync partnerships to share files on the sly with colleagues - mostly because it results in increased network overhead. With the requirement for identical local accounts, however, it's unlikely that business users will get that far.
Although buggy, the concept is good, and this is one application I'll keep looking at as the builds keep coming.