For questions about tags which are sponsored (have an icon on them) and how tags can become sponsored.
Tags with icons are sponsored tags. They cost money to sponsor, not reputation on the site. You can figure out more info on how you can sponsor these tags by checking out the advertising info link in the footer. - Grace Note
You should contact the Advertising department of Stack Overflow. The contact form is at https://stackexchange.com/about/contact (linked in the footer of each site as advertisement info and you should mention you are interested in sponsoring a tag. This includes the icon, but also a list of sponsored links (See the Android Tag page for an example). - Michael Stum
Sponsored tags have no special logic attached to them. - Jeff Atwood
A "sponsor gallery" is on the to-do list. - Alex Papadimoulis