I've been trying to get the Carambola 2 development board to recognize a Fat32 formatted thimbdrive. I don't see a SDA in my /dev folder, so I don't think it's being recognized. when I plug directly into the board the light on the thumbdrive stays lit, whereas if I plug a passive usb hub inbetween the thumbdrive and Carambola the light will light briefly, and then go out. All of the correct packages seem loaded.
Here's my relevant dmsg:
[ 14.290000] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
[ 14.300000] ehci-platform ehci-platform: Generic Platform EHCI Controller
[ 14.300000] ehci-platform ehci-platform: new USB bus registered, assigned bus number 1
[ 14.340000] ehci-platform ehci-platform: irq 3, io mem 0x1b000000
[ 14.360000] ehci-platform ehci-platform: USB 2.0 started, EHCI 1.00
[ 14.360000] hub 1-0:1.0: USB hub found
[ 14.360000] hub 1-0:1.0: 1 port detected
[ 14.470000] nf_conntrack version 0.5.0 (965 buckets, 3860 max)
[ 15.000000] i2c /dev entries driver
[ 15.130000] Initializing USB Mass Storage driver...
[ 15.140000] usbcore: registered new interface driver usb-storage
[ 15.140000] USB Mass Storage support registered.

Any ideas?

I am assuming that you have tested USB hub with thumbdrive on another system (PC or alike) and it works. First few things that you can try is see if anything else works on the hub (another thumbdrive, USB to serial adapter, etc.). Also a hub with a separate power supply would help to eliminate a possible scenario of thumbdrive requesting larger maximum current than it can support.

I also tried it with a powered hub, as well as with a USB hard drive. No difference.

After looking through the circuit diagrams and examining the board closely I found the problem. It seems there was a solder bridge across the center two pins of the USB host connector. Easy fix, now it's working great!