In keeping with the international nature of UNESCO, there is an informal understanding that the post will rotate among continents. The last three Directors General came from Asia, Europe and Africa, and there were three previous Directors General from Europe and three from North America. It appears likely that the next Director General will be elected from an Islamic member state.
The Topposts blog has a couple of clues on the nominations that have already been made.
Oman has officially nominated her ambassador to UNESCO, Musa Bin Jaafar Bin Hassan for the UNESCO DG......Bin Hassan has some credits, no least of which is his presidency over the 33rd UNESCO General Conference in 2005 - and at that time the Organization celebrated - at the highest level - its 60th anniversary.......
Egypt nominated Culture minister Farouk Hosni, the longest serving member of Mubarak's cabinet and an abstract painter who has exhibited his work around the world......Egypt's foreign minister has already met with the "working group that ran the support campaign for Hosni" (I guess, just the Foreign Ministry's experts - as of now). Considering Egypt's previous successful campaigns, Oman obviously faces a tough challenge.