Across different applications that run on datacenters, can you name applications that push multicast updates to multiple servers? Please provide name of software package for specific applications.
System imaging applications routinely use multicast. Several ( hundreds ) target systems are started for imaging work, the imaging server streams out the image data via multicast. Hundreds of workstations at a time can be prepped or imaged int his way. This can be an in-data center function for prepping blade servers, for example.
Some routing schemes I have seen will distribute updates via multicast - the routing tables are essentially a database.
I have seen memcached plumbed to recieve updated via multicast.
Video distribution is another application. Encoders and decoders will join a multicast groups forming a distributed N-way video switcher.
I would not see where multicast is really the most heavily used feature in terms of the bulk of traffic for general computing - however when it is used it is vital.