A leader of Isma‘ilis in Saudi Arabia has been released after being jailed since May of 2008; his release was part of an ‘Id al-Fitr amnesty. An English account is here; Al-Watan's account of his statement is here (Arabic). The story in itself is related in part to King ‘Abdullah's general attempts to improve treatment of Saudi Shi‘ites generally, though they are still considered heretics by the religious establishment. But most Saudi Shi‘ites (and most Arab Shi‘ites) are "Twelvers," followers of the mainstream form of Shi‘ism dominant in Iran, Iraq, Bahrain, Lebanon, and the northern Gulf generally. Isma‘ilis are another matter altogether. This story gives me an opportunity to explain who they are, since they are now rather scarce in the Arab world but have large communities in Pakistan, East Africa, and elsewhere. After all, it says up there at the top of the page that I'm "putting Middle Eastern events in cultural and historical context."
Whereas Twelver Shi‘ites await the return of the Hidden Twelfth Imam, Isma‘ilis split with the other stream over the seventh Imam, but one line of modern Isma‘ism still has a living Imam as leader of the community — that's who the Agha Khan is — while the other branch awaits a returning Imam
In the ninth and tenth centuries, under the Fatimid Caliphate, Isma‘ilism was momentarily dominant from North Africa to Syria and even, briefly, held Baghdad. But with the fall of the Fatimids Isma‘ilis increasingly became isolated communities in the Arab world, but continued to sway followers farther afield: in East Africa, around the Indian Ocean, and in the subcontinent, including what is now Pakistan, as well as Central Asia.
To oversimplify a bit, there are two main streams of Isma‘ilism today, those who follow a continuous line of living Imams, who are called the Nizaris or Agha Khanis and follow, of course, the Agha Khan; and the Musta‘li (also called "Bohra"), who await the return of an occulted Imam but are divided into various groups over which Imam was occulted; both descend from post-Fatimid imams. The Druze, who are usually considered a separate religion altogether, originated as well from Isma‘ilism.
The Nizaris are mostly in the subcontinent or Central Asia; various Bohra groups are found there and also in Yemen and adjacent portions of Saudi Arabia. This is where the subject of the story above comes in: if you look at the Al-Watan article you'll note that it is datelined Najran (for those who read Arabic). Najran is in ‘Asir, an area that was Yemeni until the 1930s when Saudi Arabia annexed it. These are Bohra or Musta‘li Isma‘ilis. There are more details on the various subdivisions in the Wikipedia article.
Some of this I know from my own studies of medieval Islam (especially of the Fatimids), but quite a lot of it I know from conversations with Abbas Hamdani, a distinguished scholar of Isma‘ilism whose daughter, now a professor in her own right, once took a course from me in my teaching days.
I know, little of this has to do with the release of the Saudi figure, but I thought the background could be useful. Since Isma‘ilis are rare today in the Arab world (a smattering in Syria I think, along with those mentioned in Yemen and Saudi Arabia, or among Pakistanis and Indians working in the Gulf), they aren't that well known to Arabs either.