9AM (officially) UK time (4.5hrs ago) the Challengers set off across Scotland.
They have 2 weeks to cross Scotland from west to east, a distance of around 320km. They are able to travel alone or in groups, and their route is of their own choosing. The only requirements are that their route is vetted by experienced walkers in the vetting team and that they regularly contact Challenge Control to advise that they are safe and on track. Challengers are free to walk the roads and stay in as many B&B's or Hotels as they can find, or stay well away from roads and camp the whole way across. Most spend at least a night or two in lodgings during their crossing and many camp every night they can.
This time of year, the weather can be either good or bad, and usually a mixture of both. On my two crossings I've had sleet and snow, hail, heavy rain and also enough sun that I have had to rummage in the pack for sunscreen.
There is a live map constantly updated from those challengers crossing with navigation gadgets: Unofficial TGO Challenge Map 2014