Oh, I love these images. Very beautiful. Could I do similar shots with my X100, or do I need a special camera or filter?
You should be able to do this Rob - the X100 has long timed exposures up to 30 sec.
You can shoot at dusk/twilight and test this out - you'll get long exposures with the low light levels. (That Palomar airport shot I did was a 30 sec exposure)
If you want to try in more normal lighting, you'll need a filter adapter ring so you can screw on a filter to reduce the light coming into the camera.
I got my ring as part of a set with the hood -
Fujifilm compatible lens adapter and hood for Fujifilm: Amazon.co.uk: Electronics
The filter ring screws onto the lens - you can then fit 49mm filters to this ring (and the hood over the top)
You'll be looking at buying a neutral density (ND) filter for long exposures - something like
Tiffen 49mm Neutral Density 0.9 Filter: Amazon.co.uk: Electronics
This will reduce the light hitting the sensor by three stops, meaning you'll need longer exposures to get a correct exposure.
You'll need a tripod to keep the camera steady during the long exposure, and use the self time feature on the X100 to delay the shutter opening by 2 secs, to avoid you touching the camera and causing camera shake during the shot.
If you need even more light reduction - then look at
Hoya 49mm HMC NDX400 Filter: Amazon.co.uk: Electronics
This gives a 9 stop reduction in light - so just 1/500th of the light hits the camera sensor. This turns day into night, and allows for very long exposures under bright lighting conditions. This is pretty extreme stuff, but Jens is in this territory for some of his shots.
. 
