We released V8 SP4 a few weeks ago and a major new feature of SP4 is Move Mailbox Archive - here's a bit more detail about what this provides.
Move Archive allows the Enterprise Vault administrator to move the contents of Domino and Exchange mailbox and journal archives to new or existing archives in other vault stores. For mailbox archives, the destination archive can be the same Enterprise Vault site, a separate site, or even a site that is located in another Enterprise Vault directory. Journal archives canonly be moved within the same site. The version of Enterprise Vault on the source and destination servers must be at Enterprise Vault 8.0SP4 or later. If an archive contains items that are under legal hold, such as from Discovery Accelerator, the archive cannot be moved. Once all legal holds have been removed, the archive can then be moved as desired.
We have also published a feature...