DebConf Organizers blog
The deadline for sponsored registration for DebConf11 in Banja Luka, originally May 8th, has officially been extended to May 19th. The reasons for the extension are as follows:
Thanks to a significant increase in sponsorship from one of our main sponsors, we have been permitted and encouraged to welcome more people to the conference. The extension is a one-off occurrence in response to this new development, and to allow any potential attendees time to access more information before registering.
Registration is required for everybody who plans to attend any part of Debconf. Access to the conference venue, food and accommodation is controlled through the registration badge. The only exception to the registration requirement is for those who plan to only attend Debian Day.
It is possible to request sponsorship for food, accommodation, and travel. Those who have been involved or contributed to Debian or to other open source projects are eligible to apply for sponsorship, which will be decided on a case-by-case basis.
The professional and corporate categories are for those who are sent and sponsored by their companies. Professional registration covers the actual costs of conference attendance, while corporate registration is just over double that price, and is aimed at those who, besides paying the actual costs, also want to contribute money and help Debian.
— the DebConf team