Scrum (Variation)
Similar to @jdv's answer, in my past 3 workplaces we used (some sort of) Scrum. Two of these were telecommunication-related. From interviews and talks with fellow developers, it seems that big telcos like Nokia, Siemens and Ericsson are adapting mainly Scrum for SW development, at least in their European development centers. I had an interview at a small financial SW firm a couple of years ago where they were using XP, but I have no practical experience with it, neither with other methodologies.
On the Scrum variations
In one company we used fairly strict Scrum. In the 2nd it was a somewhat watered down version, due to company culture, project peculiarities and personal issues. I.e. we had no single product backlog and product owner, and the sponsors kept setting us irrealistic deadlines, but our project manager was afraid of confrontation, thus he couldn't get them to understand and accept the Scrum way. (AFAIK this has improved somewhat since I left the company.) Also, we did not adjust our velocity properly, so there was always leftover in the backlog at the end of each sprint.
Another reason for this was that we were working with obscure legacy code and lots of fairly advanced math, which we were far from understanding well. So there were hidden mines in many of the tasks.
In my current place, we use a mix of Agile practices which still resembles Scrum the most (although we don't call it Scrum). However, we have a mixed group of developers, support personnel and a business analyst, the latter of which work on other projects too (or mostly). Most of the tasks are assigned to individuals at the beginning of each sprint, so team collaboration is fairly minimal. Also, for management reasons, we don't measure and use velocity, which is probably one of the main reasons we can never burn down the whole sprint backlog. The other reason, similar to the earlier project, is working with legacy code.