As already announced well change the reward system from proportional to PPLNS. This will happen on 26. Nov 2011 00:00 UTC. The first block on each blockchain solved after that date will be rewarded as PPLNS block.
If you need some more information on PPLNS please have a look at the blog as I compiled some information there:
http://blog.masterpool.eu/2011/11/pplns-facts-and-myths/If you are still missing some information dont hesitate to discuss it on the blog, the forum or on jumble.