isolated/owned would solve many problem we face right now.

[Sönke Ludwig]

Also see:
http://forum.dlang.org/thread/k7j1ta$2kv8$1@digitalmars.com
http://forum.dlang.org/thread/k831b6$1368$1@digitalmars.com

http://vibed.org/api/vibe.core.concurrency/makeIsolated
http://vibed.org/api/vibe.core.concurrency/lock

The last two links point to a working library based implementation that 
I have been experimenting with in the vibe.d. It already provides a lot 
of the possible advantages, but with additional language support it 
could be made really seamless and safe.