An explosion on a railroad on the Uzbekistan-Afghanistan border was a "terrorist act," according to local media, via RIA Novosti (in Russian). The explosion apparently happened on the line between Termez, at the southern tip of Uzbekistan, and Kurgan-Tyube in Tajikistan, between the Galaba and Amuzang stations. I can't find either of those stations on any map, but the stretch of that route that's inside Uzbekistan is pretty short, and hugs the Amu Darya river, the border between Uzbekistan and Afghanistan. The explosion took place the night of November 17, there were no injuries and local authorities are investigating.
There is very little information about this so far, but there hasn't been a terror attack in Uzbekistan for several years. And the fact that it's so near to Termez, the hub of the U.S.'s Northern Distribution Network that carries military cargo through Central Asia to Afghanistan, has to have people worrying in Tashkent and the Pentagon. This line isn't the main line of NDN train traffic, which goes a more northerly route from Termez to Karshi, which would be an argument that it may not be NDN-related. Nonetheless, the location of the (alleged) attack is suggestive. Uzbekistan President Islam Karimov's number one fear is the rise of Islamist extremism in his country, and so if this does turn out to be NDN-related -- meaning that cooperation with the U.S. has brought terrorism back to Uzbekistan -- expect discussions between the U.S. and Uzbekistan over the NDN to get a lot more difficult.
Still, it's too early to jump to many conclusions. We'll see what more information emerges.
UPDATE: A map on the Ferghana News site shows where Galaba and Amu Zang are, and it is in fact on a line that does coincide with the NDN. And a press release on the Russian Railways site (in Russian) says that service on the line is disrupted because of the "destruction of the supports of the railway bridge."