Dear all,
Discussions about privacy and what constitutes ethical research based on data from the mailing list are appearing on several threads. Association of Internet Researchers has discussed these issues for a long time. AoIR has a wiki and ethics guide http://aoir.org/documents/ethics-guide/

I'd recommend their mailing list, at least for a short time, as a quick dip into complexities of dealing with online subjects http://aoir.org/email-list/