That would be a good jump. If you are not worried about getting Bulldozer right away I would get the 955/965 black now.
If you had a x3 or a x4 I would say wait, If you do get the 955/965 the jump to bulldozer will be less of a improvement.
With the 955/965 you can make your current system last at least 2-3 years and still be happy. I have a Xeon x3350(q9450) and I will not upgrade until PCI-e 3.0 and USB 3 or 4 and SATA 6 or higher are available.