Gumstix with USB hub TUSB2036
It looks like you forgot the 15k pulldown termination resistors on DP[1-3] and DM[1-3], you can see these in the TUSB2036 datasheet in Figure 9 through 11. These resistors are part of the USB specification.
The USB signals can be connected directly to the Gumstix Overo USB connections. The easiest way to answer these type of questions is to look at the schematics for the Gumstix expansion boards, available here: http://pubs.gumstix.com/boards/ .