I'm going out on a limb here, but I "think" this how these devices work. Normally, we use a serial port in connecting a GPS device to our computers. When using a USB port, we are doing much the same, but the USB is "pretending" to be a serial port. I'm betting that Bluetooth wireless will work much the same way.
That being said, you still have the issue of using the one serial port device among many pieces of software. It doesn't matter whether it's bluetooth, serial, USB, or whatever, it's still one device. If you have mapping software, the mapping software will hog that one port with the device.
Here's where GPS Gate comes in. It takes the one device on the "serial port" (real or imagines) and 'emulates several devices on several ports allowing you to use more than one piece of software on the serial device. Each program will be assigned a different port (You will have to do this within the software).
Delorme products are indeed serial port based gps products, but.... they are proprietary in nature. They use a non-standard code that works with the Delorme software only. Now, Delorme does have a Serial Emulation software driver that chages the way the gps device behaves and makes it NMEA compliant and allows the use of the device with other NMEA compliant software.
So to use the Delorme GPS device with anything other than Delorme software, you need the Serial Port Emulation driver. To use ANY GPS device with more than a single piece of software, you need a serial port replicator (GPS Gate is one example). I believe the Delorme Driver will also allow you 2 or 3 ports as well, but honestly, I do't remember and my laptop's not in front of me at the moment.
John Diel