Does Pop-Science involvement hurt one's reputation?
If certain fields of academia do in fact frown upon "popularizing" science, then they are shooting themselves in the foot.

One of the most important ways of securing funding in different disciplines is through getting support by the federal governments in which they are working. Convincing politician X that you should fund research on doohickey X and widget Y to solve problem Z rather than funding their new shopping mall or football stadium requires convincing them that your research is important and worthwhile. The key to doing this is having a message to sell—something that the lobbyists and staff persons working for the government officials can take to them and say "this is what you need to know about why this is important."

An excellent way of doing this is to take part in writing columns, producing features for television, and other "popular" methods of outreach. You'll have to figure out how to distill your message in a way that's exciting for the viewer or reader, and that will help no only you but your peers as well.