###My take on this.

Spam is where a post does not bear a close enough relationship to the question posed, just provides links to irrelevant external material - and/or looks like self promotion to an owners website.

It appears at first glance to be on-topic & relevant.

 - http://meta.stackoverflow.com/questions/21823/what-constitutes-spam

The link in the answer seems to have some relevance to the question being asked i.e. The link provided is to an article with relevance to the question posed.

Thus to the Self-promotion issue - this should really have a pattern to this.

Having asked other MoDs from other sites (yes we have a room for just MoDs) - I just got blank looks.

I can only surmise the reason for deletion of answers from other sites was that there was indeed a pattern to the person.

On AU there doesnt appear to be a pattern of *self-promotion* (yet).  

Thus, I dont believe this falls into the spam category.

The standard comment text would apply though:

    Welcome to Ask Ubuntu! Whilst this may theoretically answer the question, it would be preferable to include the essential parts of the answer here, and provide the link for reference.