Melanie writes: I was wondering if one needs a literary agent to submit one's work or if a regular talent agent (for actors) is sufficient.
It depends. Let's say you call up NBC and say you have an idea for a show. They'll probably tell you they can't accept unsolicited submissions, and that you need an agent to have your stuff submitted. Simply to mollify their legal fears, I think a talent agent would suffice. Whether NBC would pay much attention to what you submit is another matter.
Moreover, a talent agent isn't really a long-term solution for your writing career. In my experience at the agency, I did come across some talent agents who repped a writer or two, or talent agents who helped their acting clients who wanted to try writing - but this is more the exception to the rule. I don't know a ton about the agent situations for writer-performers like Tina Fey, Mindy Kaling and Whitney Cummings (please comment if you do), but from what I've seen, most writers have a strictly literary agent. One of the many convenient things about being at a big agency with both lit and talent departments is that when clients want to try another path, they can easily reach out to the applicable department in the same agency and get expert guidance. You could have a lit agent and a talent agent on your team.
If you have a friend who is a talent agent, you should ask him/her if there are lit agents at the same agency, in the hopes that your friend can pass your stuff on to the more appropriate department. If the agent is at a talent-only agency but is willing to help (and knows whom to contact to get your writing out there), maybe you could A) have the talent agent submit your stuff to a buyer, B) impress the buyer and C) have the buyer refer you to a lit agent s/he regularly deals with. It's kind of a roundabout way to get an agent, but it happens. Some people get the agent first, then get their stuff out there. Others manage to get their stuff out there first, and then attract an agent as a result.