Jundallah

Sahimi says that there is ample evidence that the George W. Bush administration was deeply involved in funding Jundallah. While it is not clear what the policy of the Obama administration is regarding Jundallah (the State Department flatly rejected Iran’s accusations), it is unlikely that the CIA’s direct or indirect support for Jundallah has ended.
But despite its claims, Jundallah is a sectarian, not liberation, movement. It is made of Sunni extremists who hate the Shi’ites, and its goal is to foment conflict between the two sects.
There is a movement in Pakistani Balochistan against the discrimination that the Baloch people suffer at the hands of the central government. The Baloch minority (totaling about 1 million) in Iran has also been discriminated against, although the Iranian government has been trying to improve the economy there. But Jundallah is not part of either struggle. Jundallah is simply a Sunni Salafi group of the Taliban or al-Qaeda variety, believed by many to have links to both groups and to be involved in drug trafficking as well.

He makes an important point that such probably US-backed attacks act also as an inhibitor on the proposed Iran-Pakistan-India pipeline, which the US opposes:

But Iran and Pakistan have signed an agreement to construct a pipeline from southern Iran to Pakistan for transporting Iran’s natural gas to Pakistan. Initially, the pipeline was supposed to continue to India, but under pressure by the Bush administration, India withdrew from the project.

If constructed, the Iran-Pakistan pipeline, which has been dubbed "the peace pipeline," will be in direct competition with the pipeline through Afghanistan, if and when that pipeline is constructed. Instability in Iran’s Baluchestan will scare away potential investors in the Iran-Pakistan pipeline, and may prevent its construction altogether. These facts play an important role in Jundallah’s attack on Iran, but the mainstream media has ignored them.

ATonline also discusses the fact that Saudia Arabia is worried about Iran's rising influence in the region.