Despite Apple’s dominance of the portable media player market with the near ubiquitous iPod, Microsoft continues to plug away with its own offering, announcing yesterday a significant software and content update to the company’s Zune.

The Zune Marketplace (U.S.-only) has begun selling downloads of major television shows, including content from NBC Universal — a move that sticks it to Apple, following last year’s public spat between the iPod maker and major television studio, which resulted in NBC pulling its content from iTunes. Starting today, Zune users have access to 800 TV show episodes — download to-own — priced at 60 Microsoft Points each (approximately $1.99). Aside from NBC Universal, content will come from Comedy Central, MTV, Nickelodeon, among others, and will include popular shows such as “South Park”, “The Office”, “Heroes”, and “The Hills”.