As well as being the commencement of Pax Britannia/Time's Arrow week on my blog, today is the very first International Dieselpunk Day.
12 November was chosen as the date of this event because the traditional start of the Diesel Era has been considered the end of World War I, which ended on 11 November of 1918. Hence, the day after the end of WWI is Dieselpunk Day.
You can find out more about this event here and here, and who knows... maybe one day I'll write a Dieselpunk story myself. ;-)