The 9800GTX+ is NOT worth waiting for. The core clocks are not much higher.
The 9800GTX is very good for overclocking and in gaming it never really reaches 100% fan speed so you don't have to worry about it getting too hot. In rivatuner you can set it to 80% when it reaches a certain point and it won't be too loud while still cooling very well.
I bet the GTX+ will also be a bit more expensive. Not really worth especially since it doesn't save on that much energy either.
It really is up to you.