Is it to differentiate it from the visually-distracting call-to-action buttons? I suppose a follow on Twitter/email is less important than an actual download
By giving the visior multiple prominent call-to-actions, you're essensially destroying the effect of the CTA buttons, which is to guide the visitor into doing the one thing you want him to do. He won't know what you really want him to do and may not do anything at all since he's confused over what button he should click on. With too many call-to-action buttons they're essensially degraded to just being big buttons.
So, in this case, a smaller link with a nice yellow box around it is likely a better call to action as it's different from the rest of the content.
- http://pixify.com/blog/increase-conversions-with-call-to-act... (Call to Action)
- http://pixify.com/blog/use-os-x-lion-to-improve-your-ui/#dem... (OSX Lion Theme)
- http://pixify.com/blog/use-google-plus-to-improve-your-ui/#d... (Google Theme)
http://www.smashingmagazine.com/2009/10/13/call-to-action-bu...
