Yes, David. Cache-A is adding this feature on their LTO-5 ProCache and eventually all of their LTO5 products.
For Bob Cole, it helps linear tape behave more like a hard drive. LTFS is Linear Tape File System. Here's a Cache-A view of LTFS.
http://www.cache-a.com/ftpcommon/Cache-A_LTFS_FAQ_020411.pdf
Jeremy