There always seem to be confusion over this subject, for as long back as I can remember and before forums and so forth became so popular. There's also still confusion about code written at work, both by employees and contractors - I'm not aware of the differences between US and here in the UK, never been bothered particularly.
If you post/publish code/articles etc. you're putting it into the public domain ( for others to do with as they see fit ) as to who "owns" it - well if I post code on a microsoft msdn forum does microsoft own it ?
I'm still slightly worried about the Redgate ownership ( not for this reason ), but as to publishing code/articles - if you write something good hopefully others will want to use it, why else submit/post - the obvious concern is plagiarism and this does tend to happen, copyright or not.