I'm not affiliated with Dlink, but let's say I keep my comms open...

Anyway, I don't know yet if the current issues that came up after the 1.31 release will truigger more firmware updates.
Looking at the WA (wifi alliance) schedule the formal sign off is planned in feb/march 2010. I think it really depends on how the process with WA wil go ánd how the final specs will be. So you won't see any guarantees from manufacturers about updates to the final N specs.
But if the specs will remain the way they are now in the draft N proposal, you won't have any benefit from a 'final N' version.