Windows 7 introduces a new feature for Offline Files & Folders called “Transparent Caching”. With transparent caching, the first time a user opens a file in a shared folder, Windows 7 reads the file from the server and then stores it in a cache on the computer’s hard disk drive. The second and subsequent times a user reads the same file, Windows 7 retrieves the cached file from disk instead of reading it from the server. To provide data integrity, Windows 7 always contacts the server to ensure the cached copy is up-to-date. The cache is never accessed if the server is unavailable and updates to the file are always written directly to the server. ransparent Caching is not enabled by default and can be enabled through Group Policy at Computer configuration | Administrative Templates | Network | Offline Files | Enable Transparent Caching.
More info: Kurt Roggen