On January 11 the LTO group announced the specifications for LTO-4. This means that manufacturers can start to develop products around the LTO-4 specification. However we are not likely to see anything, at least anything affordable for a few months.

Pros

• Products based on LTO-4 expected in the first half of 2007
• Doubled capacity to 800 GB native (1.6 TB compressed)
• Added drive level encryption
• Increased data transfer rate to 120 MB/sec.

Cons

• Dropped support for reading LTO-1 tapes

Official announcement from the LTO group:
http://www.lto.org/newsite/html/news_1_10_07.html

Articles about LTO-4:
http://weblog.infoworld.com/tcdaily/archives/2007/01/lto_4_brings_tw.html
http://networktimes.co.za/news.aspx?pklNewsId=23344&pklIssueId=611&pklCategoryID=207