In a report today, Mikko of F-Secure indicated that a spammer is apparently concerned that an e-mail collecting spider might find their e-mail address (firstname.lastname@example.org) and add it to a spam database. Because of that concern, Mikko illustrated how the spammer used info [at] bulk-mail [dot] org instead of email@example.com.
I agree with Mikko that it is probably not a good idea to post firstname.lastname@example.org to a public web page or they might get spam. Now wouldn't that be a shame if the spammer got spam?
See Mikko's report about email@example.com at Do spammers get spam?