I organize the ACE! Conference each year. It attracts people in the business of software from all over Europe.
Most of the attendees are programmers or project managers in European software companies.
The t-shirt design should be striking and memorable, something that software people would wear to work. It should look good on different color t-shirts (attendees can choose between white, black, red, and blue). I'd prefer a two-color process, with three at most. The final design should be delivered in a format which can be handed to a screen printer. The name of the event is the ACE! Conference. I'm re-branding it from Agile Central Europe, so that name should not be used. The graphic of the swift (the bird) may be incorporated in any creative way that you see fit, and the eps of last year's logo is attached for your consideration and use, but the exact logo should not appear in this form on the shirt.