Since the list is dedicated to interactively researching vulnerabilities, there will there will generally NOT be an opportunity to warn software vendors or authors. In many cases it will not be clear that there is a problem until the exploit or description is finalized, at which point all list subscribers will know. It is very appropriate to notify vendors or authors as soon as it is clear there is a problem. The subject of whether or not full disclosure is a good idea is not open for discussion on this list. The VULN-DEV mailing list is a lightly moderated mailing list to facilitate the open exchange of security holes and related information.
Moderation is in place to control spam, flames, off-topic discussion, and to kill tired threads.
If you're not sure if it applies or not, go ahead and post it. If it's not security related, then either the moderator will stop it or the list members will point it out. The DEV in VULN-DEV should give some indication to the spirit of the list. This is a developers list. We research vulnerabilities and develop exploits.