By Gordon Corera
Security correspondent, BBC News
Bin Laden's appearance ended rumours of his death
Six years on, the notion of al-Qaeda being on the run appears outdated and misguided. Instead, the group has adapted and looks resurgent on many fronts.
Osama Bin Laden may have recently made an unusual appearance in his first video for nearly three years, but his importance is generally thought to have been limited by his need to keep a low profile for fear of being caught.
Instead, recent events in Europe, with arrests in Denmark and Germany, as well as attacks in North Africa, have made that resurgence clear, and particularly highlighted the trail back to al-Qaeda's leadership.
The cell disrupted in Germany last week is a sign that the model of operations the UK has seen in recent years - so called "home-grown" suspects receiving training and direction from the al-Qaeda leadership in Pakistan - is now spreading to other European countries.
The training camps are much smaller than the large static pre-9/11 camps in Afghanistan but do offer the chance for recruits to develop crucial expertise in areas like explosives.
In some cases, individuals appear to be travelling out to camps not directly associated with attacking Western targets but centred on training fighters for conflicts in places like Kashmir or Central Asia.
But al-Qaeda recruiters will "talent spot" Western individuals from these camps and offer them the chance to move on to more specialised training.
Anti-terror officials believe the group is entrenched in Waziristan
The recent peace deal between the Pakistani government and tribal groups in Waziristan is seen as a huge mistake by counter-terrorism officials in the West.
They believe it served to entrench the position of foreign fighters and al-Qaeda, giving them the chance to regroup, rather than seeing them driven out as was the stated aim.
It has also allowed channels of communication and direction from the al-Qaeda leadership to different groups around the world - which were disrupted post-9/11 - to be reinstated.
The German authorities say that as well as attending training camps in Pakistan, the men arrested last week were receiving direct orders from the region on when to carry out an attack.
US intelligence appears to have intercepted some of these communications.
One of the concerns is that while electronic surveillance is technically possible, the most effective form of intelligence gathering would be human surveillance - following people in and out of the country and placing spies within the camps.
But human surveillance is considerably more challenging, largely owing to the volume of travel to the region and the scale of resources required to cope with it.
Suspects in recent European terror plots have been domestic nationals
For al-Qaeda, using "home-grown" suspects is far easier in terms of having them return to their country of origin and put in place planning for attacks.
So far this threat may have manifested itself most obviously in European countries, but the US continues to worry about operatives attacking the US or entering the US from Europe.
Many European countries have visa-waiver agreements with the US, making it easier for their citizens to enter and easier for them to blend in.
CIA director Michael Hayden reiterated last week that the US intelligence community strongly believed that al-Qaeda's central leadership was "planning high-impact plots against the US homeland".
Al-Qaeda has "protected or regenerated key elements of its homeland attack capability" from its safe haven in Pakistan, he said.
The signs of a regenerated al-Qaeda are evident not just in recent activity in Europe but also in other parts of the world, as well as in the crucial battleground of the media.
North Africa is one arena in which al-Qaeda has clearly become more deadly in the last year.
This has followed the move by the Salafist Group for Preaching and Combat (GSPC) to change its name to al-Qaeda in the Islamic Maghreb and begin a new campaign of violence in Algeria.
Fifty-seven people have been killed in two attacks this month. In April, suicide bombings killed another 33.
Responsibility for the latest attacks was claimed in an internet statement by the group and it has generated an increasingly active propaganda campaign.
The organisation is media savvy and has its own production company
It is in the field of information and media that the resurgence of al-Qaeda is most evident.
At least 74 videos have been released by al-Qaeda's production arm, as-Sahab, in 2007.
This is compared with only 16 in 2005 and 58 in 2006, according to the organisation IntelCenter which monitors their distribution.
Most analysts agree that it is the ideological struggle - the battle of ideas - that has become crucial in recent years, especially as al-Qaeda's sophistication in putting out its message has grown, and as it continues to try and radicalise and recruit Muslims from around the world.
Mr Hayden called the struggle to counter this jihadist ideology "the deep fight", but it is the fight which the US and its allies look least like winning at the moment.