After some online help, I found a way to get the follower count for a pinterest profile using Nokogiri gem and scanning the meta tags.
If you run the following in ruby console to output the document for this url:
require 'open-uri'
doc = Nokogiri::HTML("http://www.pinterest.com/pinterest/")
Now you can extract the meta tag for the followers count as follows:
doc.xpath("//meta[@name='pinterestapp:followers']").first.attributes['content'].value
The above is possible because the pinterest profile page source has the following tag (View Source for the page):
<meta property="pinterestapp:followers" name="pinterestapp:followers" content="432444" data-app>
Till the time we do not have an api for pinterest, this seems to be the way to get the followers count for a pinterest profile. Hope this helps someone!