SharePoint provides a base of social networking capabilities (more on SharePoint social networking features here). This includes the Colleague Tracker which is a web part on your SharePoint My Site showing updates on what's going on in your network of colleagues within the enterprise. So for example, when a colleague has a new phone number or have changed position, the Colleague Tracker will tell you this. It also shows what documents your colleagues are working on and what workspaces they become member of. It introduces an amazing level of visibility and can be a serious booster for collaboration.
The Colleague Tracker can report on any user profile property, including all your custom ones. When you create a new profile property through the SharePoint SSP there is an option to select whether changes to this property should be shown in the Colleague Tracker.
The user profiles can be extended with properties being imported through SharePoint's Business Data Catalog. This means that employee data from your ERP system, such as organisational unit, cost centre and job title can be imported from the source of truth to your SharePoint user profiles. And when those properties are configured, there is an option to track changes to them with the Colleague Tracker.
The result is a social networking experience in SharePoint which is integrated with your ERP system. When you change position, organisational unit or location, your colleagues will automatically be notified of this.