I have not timed it but there is the wifi sharing alternative - no cable needed. You just drag/drop files from the Windows' Explorer program (is there a mac equivalent?)
There is some thread about 5 times faster but I don't recall the details.
If you're only getting 2MB/s over your usb cable, you most likely won't get any faster speeds with wifi file-sharing. In regards to the 5x faster comment, I believe it works the other way, using the usb cable is faster than file transfers over wifi.
My Playbook usually runs anywhere from 3-5MB/s using the cable, and less than 1MB/s with wifi file sharing, though this just might be an issue with my laptop as I get really slow wireless transfers between other computers and my laptop as well.
Regardless of speed, wifi file sharing is definitely convenient! If you haven't set it up already, everything you'll need to do is in the Options menu under Storage & Sharing.
