The OSGi Alliance is where all the OSGi specs are developed as a collaboration effort of a number of companies (and sometimes invited researchers). To be able to contribute to specs you need to be a member. There are a number of reasons for this but probably the most important one is proper handling of IP flow.
In the past a number of people have told me that they would be interested in taking part in the specification work at OSGi but they simply could not afford the membership. Well for those people there is good news today. The OSGi Alliance has moved to a new membership structure where much cheaper options to become a member are available. Also the size of a company is taken into account at certain levels where smaller companies (under 250 employees) pay less.
There is also an entirely new type of 'low-fee' membership: Contributing Associate (which replaces the old Adopter Associate). Being an Contributing Associate is much more useful than Adopter Associate was as Contributing Associates can send up to 2 delegates to Expert Group meetings (such as the Enterprise Expert Group) where they can fully participate in the development of RFPs and RFCs, which ultimately can become OSGi specifications.
Any existing Adopter Associates are automatically moved to Contributing Associate, so they can start contributing right now! (well, you need to sign some docs, but that's all).
Ideally you want stuff like this to be free, but as any Standards Development Organization, the OSGi Alliance (which is a non-profit organization) has operating costs and the membership fees are used for that. As a representative on the Board of Directors I will always make sure that any money in the organization is used appropriately.
I'm personally very happy to see the OSGi restructuring finally taking place. I expect that it will open the door to more participation, especially from the large number of smaller companies who are successfully using OSGi in the field. The OSGi technology is great, but great things can always be improved. Doing this in the OSGi Alliance means that those improvements will be embodied in specifications and specifications ultimately lead to choice as multiple implementations can co-exist so that users will be free from vendor lock-in.
For all the details of the new membership structure see here: http://www.osgi.org/About/Join and here: http://www.osgi.org/About/Benefits#compare
Alternatively, feel free to contact me at email@example.com if you have questions, I may not be able to answer all of them but I can always point you at the person who does.
For a list of current OSGi specifications and their implementations see here: en.wikipedia.org/wiki/OSGi_Specification_Implementations