I purchased a Dynamode USB Hub for use with my Pi. It's a 7 port self powered HUB. The hub is the same as those being sold at Farnells as being compatible with the Pi. (http://uk.farnell.com/dynamode/usb-h70- ... dp/2115058 is the URL for the hub).
The hub claims to be USB 2.0 Standards compliant but is not for the following reasons:
1. It feeds power back up the interconnect to the Pi. Section 7.2.1 of the standard says that "No device shall supply (source) current on VBUS at its upstream facing port at any time. From VBUS on its upstream facing port, a device may only draw (sink) current."
2. It should supply 500 mA to each of the 7 USB ports, but the power supply is only rated at 5V 1000 mA in total. For a 7 port hub, it should be rated at 3.5 A I would imagine. As Section 7.2.1 says, "Hubs that obtain operating power externally must supply five unit loads [500 mA] to each port."
I've sent mine back for the above reasons, plus, it doesn't work with the Pi. I'm not sure Farnells should be selling this hub as being compatible with the Raspberry Pi. (Plus, the pdf download with the Hub specs is for a completely different hub!)
Other problems I have found with this hub in testing it are:
1. The power back feed as mentioned above.
2. With the interconnect cable disconnected, it cannot even power the Pi!
3. With the hub connected, the Pi will not boot.
4. Booting the Pi, and connecting the hub causes the network to stop working.
5. The power lead is about 45 cm/18" long.
6. So is the interconnect cable.
All in all, not a good buy - other than good by to my postage and packing for sending it back.

Cheers,
Norm.