I can confirm this is working with Tenda W311U 150Mb usb adapter. The chip reported by lsusb is actually 148F:3070 which would mean Ralink RT3070 but since I had no patch for RT3070 driver I decided to use 2009_0820_RT2870 driver and the patch supplied by Bryan.
I blacklisted rt2800usb and also rt3070sta (which was a result of my previous compiling of the RT3070 Ralink driver but without patch and it didn't work).
I also used the # hack for wireless Bryan posted.
After that my W311U is able to create ad-hoc wireless network with 150Mb speed. I am only using it for that and have no networks around me to test more.
Just another note, blacklisting rt2800usb made Karmic try to use rt2870sta driver which comes with it but for my adapter that wasn't working well. The network created was reported with speed 1Mb and my netbook very close by couldn't connect at all. I don't know whether the patch did the job, or a combination of the Ralink RT2870 driver and the patch, but in my case don't count on the built in rt2870sta after blacklisting rt2800usb. Compiling took just few steps and it worked for this adapter.