So, in a nutshell, the DV4 Mini is a low power UHF transceiver and network gateway in a single USB interfaceable stick. The RF side is the "link" between your handheld and the stick. The USB side is the "link" between the stick and the DMR/DStar/P25 reflectors that they have been given the OK to connect to. My hope is that someday they'll have a way to connect to the DMR-MARC network and remove the need for a complete Motorola MotoTrbo repeater to get on the network.
I went back through the last few pages of threads and didn't see any discussion on the DV4 Mini dongle that is coming out of Germany:
DV4mini USB Stick for D-Star and DMR - HELITRON Online Shop
Looks like there is a US reseller gearing up to ship next month:
Wireless Holdings, LLC
You can download and install the DV4mini software from Index of /V1.6
Here is a facebook group everyone can join for help and support with the DV4 mini https://www.facebook.com/groups/10025
I found the DV4mini manual . It looks like the software will support reflectors on D-Star, DMR, Fusion, and P25.
Fusion Reflector - not a Yaesu sanctioned reflector I assume (i.e. not accessible via a WIRES X box)
P25 Reflector - I didn't know such a thing existed