A list of similar projects, as well as some hastily written comments comparing them to the angel-app (you may also find these links to be useful):
http://www.box.net : Transparently store your data on a centralized infrastructure, i.e. data storage depends on the service provider.
http://www.allpeers.com/ : Share your data with your friends via a p2p mechanism. Storage mechanism is not a priori redundant, but requires the peer user to perform an explicit pull request.
http://www.coralcdn.org/ : Data is not encrypted. Data redundancy is based on view demand rather than on storage lifetime considerations. Data manipulation is not integrated with standard file system operations.
http://www.powerfolder.com/ : Similar to http://www.allpeers.com . Data synchronization requires the user to perform an explicit push/pull operation.
http://mnetproject.org/ : seemingly dead.
http://hivecache.com/ : seemingly dead.
http://freehaven.net/ : the following remark from http://zgp.org/pipermail/p2p-hackers/2002-September/000830.html probably applies:
This is a simpler version of the Free Haven [1] problem. Basically, in Free Haven we want to do this while maintaining censorship-resistance. This implies hiding the location of each server.
http://wiki.apache.org/lucene-hadoop/ :
Hadoop's Distributed File System is designed to reliably store very large files across machines in a large cluster. It is inspired by the [WWW] Google File System. Hadoop DFS stores each file as a sequence of blocks, all blocks in a file except the last block are the same size. Blocks belonging to a file are replicated for fault tolerance. The block size and replication factor are configurable per file. Files in HDFS are "write once" and have strictly one writer at any time.