Microcontroller Bluetooth Multiple Connection Support
The Verdex Pro XM4-BT uses the Intel UniStone PBA 31308 Bluetooth module.  You can find full product details in their datasheet.  In brief, it supports 2 synchronous SCO/eSCO links, which is clearly not enough for triangulation.  It does, however, support 7 point-to-multipoint connections.  I haven't spent a lot of time with Bluetooth's inner workings, but what I think that means is that you should be able to quickly switch between paired devices and collect RSSI data from two of them at a time.

Hope this helps.  If you have any other questions about Verdex Pro, or any other Gumstix COMs, I'd be happy to help out.