I am running ubuntu on various computers on a home wireless network. Some are on 9.04x64, some 10.04x64 and one 9.04x32.
scp with a large file starts out at 2.1 mbps and drops down to about 200k, stalling and dropping until the transfer is complete. I've noticed this when I have a secure shell open on any of these servers as well.
I have tried this with 2 different routers, both brand new, different brands.