Hi,
there is new MapDB3 milestone 2 release. It adds improved BTreeMap and much faster SortedTableMap.
Blog post also discussed roadmap for stable 3.0 release in March.
http://www.mapdb.org/blog/m2_and_roadmap.html
Maintenance releases for 1.0 and 2.0 branches will be some time next week.
Regards,
Jan Kotek