When civil unrest first erupted in Tunisia, the markets, perhaps with some justification, paid little to no heed. While the upheaval came as more than a bit of a surprise, given the fact that Tunisia has long been one of the more stable and progressive countries in the Middle East, there was no real reason for the market to pay much attention.
Tunisia has a fairly diverse economy, and is not a notable producer of oil. The mining sector is an important one, but the "heavyweights" are iron ore and phosphates, according to the World Fact Book.
Unfortunately, what the Western world considers a "democratic" government is pretty much non-existent in the Middle East, with the exception of Israel. The various regimes holding power range from somewhat to extremely authoritarian and repressive.
Now, like a wildfire fanned by high winds, (although in this case, the internet and social networking sites), the unrest has spread to Egypt, which puts a much more ominous spin on events, which are impacting both the oil as well as precious metal markets.
While Egypt produces and exports some oil, and LNG, its not an especially "heavy hitter" in that regard. The problem roiling the markets stem from the Suez Canal. A major transit route of oil and petroleum products from the Middle East to Europe, that typically handles 3 convoys of tankers a day. Bloomberg News already has reported that shipping companies have taken to re-routing their ships to avoid having to transit the canal.
Alternate routes will add 30 to 40 days to voyages, and will add supply side pressures to increase, at least in the short term. I'm thinking that there's sufficient excess tanker capacity, so - should present political unrest continue for an extended period of time - the glitch in oil deliveries will be resolved, although I would expect upward pressure on spot tanker rates.
Yet another, perhaps larger concern, should civil unrest continue to spread throughout the region, lies with Yemen. Lying adjacent to Saudi Arabia to the southeast, there's been a steady series of clashes along the border between Saudi Arabia, and Yemen for quite some time, leading to the upgrading of defenses and barriers by the Saudis. Despite declining oil production, Yemen still currently produces an estimated 288,400 bbls/day, according to the World Fact Book.
Finally, it's entirely possible that the linchpin of OPEC, Saudi Arabia, could fall victim to any widespread regional upheaval. Like many of the middle/central European countries, Saudi Arabia is an amalgam of numerous tribes that were coalesced in 1932 by Abdul Aziz ibn Saud into the Kingdom of Saudi Arabia. (Note: Matthew Simmon's "Twilight in the Desert" starts out with an excellent history of the formation, and early days of the Kingdom, making the book a worthwhile read for anybody with an interest in oil, regardless of whether or not they agree with Simmon's conclusions).
I would think that the price of Brent would spike, widening its spread in relation to WTI, given relatively high Cushing inventories. This is assuming that the unrest remains contained, and doesn't spread to Saudi Arabia, or any of the other large Middle Eastern oil producer/exporters. In addition, as noted above, look at continued upward pressure on the tanker companies that focus mainly on the spot market, as opposed to long term charters, such as (FRO).
Sources: The World Factbook, Bloomberg.com, "Twilight in the Desert"