[I edited the post below (without showing changes) to update it to include the information I was seeking with my original post.]
Announcement on London's Operation 7/7/2005
Jamaat al-Tandheem Al-Sierri (secret organization group)
Organization of Qaeda't al-Jihad in Europe
In the name of God the most merciful...
Rejoice the nation of Islam, rejoice nation of Arabs, the time of revenge has come for the crusaders' Zionist British government.
As retaliation for the massacres which the British commit in Iraq and Afghanistan, the mujahideen have successfully done it this time in London.
And this is Britain now burning from fear and panic from the north to the south, from the east to the west.
We have warned the brutish governments and British nation many times.
And here we are, we have done what we have promised. We have done a military operation after heavy work and planning, which the mujahideen have done, and it has taken a long time to ensure the success of this operation.
And we still warn the government of Denmark and Italy, all the crusader governments, that they will have the same punishment if they do not pull their forces out of Iraq and Afghanistan.
Here are portions translated by AP-Cairo and Spiegel Online.
"Rejoice, Islamic nation. Rejoice, Arab world. The time has come for vengeance against the Zionist crusader government of Britain in response to the massacres Britain committed in Iraq and Afghanistan."
"the heroic mujahedeen carried out a blessed attack in London, and now Britain is burning with fear and terror, from north to south, east to west."
"We warned the British government and the British people repeatedly. We have carried out our promise and carried out a military attack in Britain after great efforts by the heroic mujahedeen over a long period to ensure its success."
"We continue to warn the governments of Denmark and Italy and all crusader governments that they will receive the same punishment if they do not withdraw their troops from Iraq and Afghanistan."
I enabled comments for 2 days and I'll leave them on even though I received the translation I was requesting.
"Rejoice, community of Muslims."
"The heroic mujahedeens today conducted an attack in London."
All of Great Britain is now shaken and shocked, "in the north, the south, west and east."
"We've warned the British government and the British people time and again."
"We've kept our promise and have carried out a blessed military operation."
"We continue to warn the governments of Denmark and Italy and all other crusader governments."
"Secret Organization — al Qaida in Europe."
ADDITIONAL UPDATE: A new post contains the BBC's complete translation.