Are alternative metrics taken seriously by hiring committies? Knowing that there are some members of hiring committees here, I am hoping for some insights.

Having read Rise of Altmetrics, I started to wonder what would be the best way to measure the impact on my publications. I do care for many reasons but one of the reasons is to impress others enough to be able to get a job/promotion/tenure.

So, my question is, do hiring committees take alternative metrics (Facebook likes, mentions in blog posts, etc.) seriously when trying to measure the impact of someone's work or are other issues like impact factor more important?

This question is related but is more about measuring the impact of a journal but my concern is measuring the impact of my own work (which might be in several journals).

This question is also related by asking how impact measurements affect job prospects and has some excellent answers but my question is specifically about 'unofficial' metrics like tweets, downloads on SlideShare, etc.

This question is also related asking how to measure readership of journal articles but my question is whether alternative measures are taking into serious consideration but those making hiring/tenure decisions.

I know there is the h-index (with its own flaws) but that seems to measure my publications as one unit (all publications taken together, therefore measuring me overall). I'm more interested in measuring the impact publication by publication in order to show an improving trend.

On a side note, it seems that there is a general feeling that a publication in a high impact factor journal equals a high impact publication. This feels a little off to me since one might convince the editor their work is important while at the same time fail to convince their academic community of the same.
I served on a hiring committee in mathematics at a research university in the United States, and I don't believe that any of us paid attention to the sort of metrics you describe. 

My personal inclination is that I would not recommend listing any of this information unless it is unusually notable, e.g., if someone particularly well known blogged extensively about your work. However, different countries, universities, and departments might operate differently.