Professional Plone Development
I'm happy to add, albeit belatedly, T-Mobile to the list of relatively large and well known companies that have adopted Plone. [Disclosure: I work for the responsible contractor. :)]
T-Mobile uses Plone internally Europe-wide (11 nations, 10 languages) enabling centralized managing and local printing of sales material at the PoS on demand.
I'll have a case study for plone.net ready soon, but in the meantime feel free to mail me if you have further questions.
Vidar Andersen, Co-Founder of the Plone CMS