Does Java 6 support 10 gig ethernet out of the box?
It seems like it shouldn't require Java changes, but I thought I remembered that Java 7 was adding 10 gig support.
Java doesn't care about the underlying network infrastructure when it uses sockets, etc. If 100Gbit Ethernet was invented tomorrow, Java would support it.
So, basically, the answer is yes.
I'm not sure where you found the 10Gbit; it might be some other Java-based product.