Delta Based File Compression from MS for Windows (Beta)

Delta Compression Application Programming Interfaces

"Delta Compression is a differential compression technology developed by Microsoft. While it has mainly been used for Windows Updates, Delta Compression offers other uses as well. The following topics discuss Delta Compression Application Programming Interfaces (APIs) currently available in the Windows Platform.
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PatchAPI
C-Language based API that allows you to create and apply deltas.
Lower computational overhead than MSDelta but typically creates larger deltas.
Applies to:
   Microsoft® Windows XP®
   Windows 2000®
   Windows Server 2003®
   Windows Vista®
 
MSDelta
C-Language based API that allows you to create and apply deltas. MSDelta offers optimization for a much larger range of file types than PatchAPI.
Applies to:
   Microsoft Windows Vista
 
This documentation is intended for software developers who want to programmatically create deltas (patches or compressed diffs) between files. General information about the various APIs is included in this documentation. It provides information about delta compression and the Delta Compression APIs. This documentation provides descriptions of the functions as well as supplemental information for developers who want to optimize the size of their deltas for certain file types.
 
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The MS Delta made me chuckle... Raise your hand if you ever used MS Delta (the predecessor to SourceSafe) [Hand Raised]

In any case, these API’s look interesting. It would be cool see something like this built into one of the auto app update methods (App Update block, ClickOnce, etc).