Does the word "newbie" have a negative connotation?

When it started in [who knows? See Mark's question on the word's origin] it was, if not derogatory then certainly condescending.

It can be used in a tone of "friendly ribbing", but that's true of other terms that would be considered derogatory when there's no other context to reposition it.

It's not considered explicit, so you could safely use it of yourself in a self-deprecating manner without much risk of people taking offence at the word itself.

To use it of potential customers, you'd have to be confident that the informal and fun tone had already been set. If so, then it could well work, but it could definitely backfire too. vBulletin's default member levels jokingly mock both new and more senior members by having "cool newbie" as the starting level, and "no life" as one of the more advanced levels. Since "no life" would generally also be seen as derogatory, this gives an insight into the way "newbie" can be taken here - it's an insult, but the tone is set so that mild insults are to be taken as a joke. There are businesses that can work with that tone, but most could not.

"Newbie" probably owes much of its widespread use to Usenet, where it definitely had negative connotations. In general, yes, I'd say calling someone a Newbie would be negative. The implication is not just that someone is new, but that they haven't "done their homework".

Having said that, there are clear examples of people using words like this in a way that gives a positive message. The publishers of the Dummies books did very well out of taking a negative word and giving it a positive slant.

Of the 17 general references for newbie listed in Onelook.com, 15 denote newness and inexperience, without discussing any negative connotiation.

Only two suggest a negative implication:

The Word Spy suggests that it can be derogatory:

A new or inexperienced user, especially one who is ignorant of netiquette and other online proprieties.

They offer an example:

There is nothing inherently bad about being an inexperienced user. It's only when the inexperienced ignore those rules that serve to grease the wheels of Net social interaction that they get branded with the 'newbie' label.

Wikipedia also suggest the possibility of negativity:

It can have derogatory connotations, but is also often used for descriptive purposes only, without a value judgment.

It is likely that many newcomers would not take offense at an acknowledgement of their lack of experience, but some may bristle.

One possible origin of "newbie" seems to have been in the US military back in 1969.

I can assure you that when I myself was a "newbie" in the US Army in the 1980's, the term was quite derogatory, and not uncommon, at least in the vocabulary of my drill sergeants.