Under U.S. and international copyright law, the copyright in a written work, such as an e2 write-up, is owned by the creator of the written work, and it arises as soon as it is fixed in a tangible medium - i.e. posted to e2.
In other words, you, the writer of a write-up, own the copyright to that write-up, and have the exclusive rights to that write-up for the time allowed by law - effectively, for your lifetime. You don't lose that right unless you abandon or transfer the right to someone else.
For example, the Hotmail user agreement provides (unles they have recently changed it) that anything sent over Hotmail's facilities becomes the property of Hotmail. So in effect, if you send your latest draft of the Great American Novel to your editor via Hotmail, you've just given the novel to Microsoft. (To date, they have not tried to enforce this and it might not even be upheld by the courts, but the implications of the user agreement are clear.)
In my short time here, I have not been party to any such user agreement for e2. In the absence of such an agreement, the copyright for these written works remains with the authors.
UPDATE: From the E2 FAQ: Who "Owns" What In E2?:
Users "own" the content of their nodes. E2 simply reserves the right not to always publish them. E2 will not use them in the publication of books or other Web projects. E2 does not (and most likely will never) profit from anything you post on E2. Except by the ways you enrich the website by your presence and contributions.
So I guess that settles that. (Thanks to heyoka for the tip.)
Disclaimer: This is for informational purposes only and is not intended to be legal advice. In the event this were actually legal advice, your wallet would be much lighter. This write-up void where prohibited. Readers located in jurisdictions where I am admitted to practice law, and those outside jurisdictions where I am admitted to practice law, should disregard this write-up except as an intellectual novelty. If you require legal advice, hire a lawyer.