"Iran Revolutionary Guard Corps (IRGC) xxxxxxxxxxxx told London Iran Watcher xxxxxxxxxxxx that Iran's cooperation on security in Iraq, though not yet evident, would be forthcoming, but in the same breath argued that a U.S. terrorist designation of the IRGC would prevent any such cooperation."
There has, for a long time, been a movement to have the Iranian Revolutionary Guards listed as a terror group in the west. There are clear terror links to them and they have a history of support for terrorism.
The leak helps explain why that designation may not yet have occurred.
The cable also confirmed the role of Iran in formenting terror and violence in Iraq and Afghanistan:
"for the USG to hold its hand on designation came xxxxxxxxxxxx engaged with the invited group at length on Tehran's view of U.S.-Iran relations, Iraqi security, and the nuclear issue. xxxxxxxxxxxx candid remarks, which included extremely vigorous exchanges with xxxxxxxxxxxx alternated between aggressive characterizations of Iran's relations in the Persian Gulf, admissions of the IRGC's presence and role in Iraq and Afghanistan, and apparently earnest statements of Iran's desire for cooperation with the United States."
Yet despite their remaining off the US State Department's list of terror groups, the Iranians failed to keep their word, as a subsequent cable in 2009 reveals:
Islamic Revolutionary Guard Corps - Quds Force (IRGC-QF) officers are active in Iraq, conducting traditional espionage and supporting violent extremists as well as supporting both legitimate and malign Iranian economic and cultural outreach. Iraqis and their government have demonstrated increasing willingness to push back against malign Iranian influence in the last year. Working with the Iraqis, we have succeeded in stopping some IRGC-QF activity through military operations and diplomatic engagement, while we prevented some IRGC-QF officers from entering Iraq through explicit warnings that we would target them unilaterally.
You can read the entire 2007 wiki leak below (click each one to enlarge)