I mixed both PROs and CONs, since it is difficult to make a hierarchy of thoughts, when you are so involved as I am.

1. Open Source is a great adventure, in which you encounter some very nice people, and learn from others;

2. Open Source does not give a lot of benefit, neither financial, nor for fame (do not expect much reward);

3. Select a permissive license (like MPL), and/or a GPL/LGPL license since it is needed for such viral projects - but I do not know many Delphi software created as GPL/LGPL;

4. Release soon: do not wait to post the code - when it works (compile + pass the regression tests), submit it, even if it is not perfect;

5. Release often: use a source code repository, and post every modification in it;

6. Do not leak the features you need on your side for a particular client - it smells like wrongly designed code in your libraries, which may not be open enough for extension;

7. If you publish a library, try to document your code, and follow coding/naming conventions - if you do not have time for documenting, try at least some wiki;

8. Have a forum for support, but do not expect other users to help - usually, only the main contributors will post on the forum - others may feel too shy;

9. Be gentile and patient with every user (unless he/she is a troll or openly incompetent), and be enthusiast with any code contribution (if you can, integrate it ASAP in the trunk);

10. Most of your users will ask for free support, or even debugging of their own code - learn to say NO;

11. Feedback is welcome, even from people who do not like what you and other contributors did;

12. If you are several co-workers working with your libraries, let everyone be involved in support;

13. Have a bug tracking web site, and distinguish bugs from feature requests;

14. Set priorities to tickets, especially feature requests: implement first those YOU need, then those you may be paid for, then those you may have fun working on, then let people contribute on their side for the remaining;

13. Use your public web site to track and discuss any bug or feature request you encounter on your side about the libraries (it will benefit all);

14. A set of regression tests with good coverage is mandatory;

15. You can offer support for your libraries for money, but you will be only asked on a few occasions;

16. You will have companies or individuals ignoring your libraries (why was our blog never accepted in DelphiFeeds? or rejected from Delphi GetIt), perhaps because they do not understand Open Source, or see it as some "unfair" competition;

17. Do not hide anything, even restrictions nor known issues;

18. Try to make your site appealing, but do not abuse of marketing - good marketing and wrong code did kill the component market - good code is the priority;

19. Do your best to support several versions of the Delphi compiler - a lot of users, especially in Open Source, are still using old (pre-Unicode!) versions;

20. Design and architecture level of some Delphi user is somewhat low - most did use the tool in pure RAD, and are afraid or ignorant about modern programming (like SOLID, DDD, stubbing, unit testing...);

21. If you incorporate some code from other Open Source project, clearly state it (good), or rewrite it from scratch (even better - with the corresponding unit tests);

22. Delphi is a very small market, not trendy, especially for young developers;

23. Open Source your libraries can be time consuming (e.g. if you are as perfectionist as I am) - but the main point is about balancing your investment, with the benefit of sharing;

24. Thanks to a larger base of users, you will find bugs you would never discover otherwise, but on production (e.g. with Asiatic Windows, or on heavy production);

25. Participate to the Delphi community outside of your own project(s), e.g. on StackOverflow or Google+ - it will help ranking your web site;

26. Your code will remain for ever on the Internet archives, and you will never be forgotten;

27. Even your managers can be convinced about the (financial) benefits of Open Sourcing some code, and also that you may spend some (identified) part of your time to maintain a community;

28. Sharing is everything.

Feedback is welcome in our forum!