Showing no signs of backing off its effort to be the No. 2 in the digital music wars, Microsoft has a new line of Zune devices and upgrades to the Zune Marketplace service.

The new devices, unveiled today (Oct. 3), include two flash-based devices -- a first for the Zune line, including a 4 GB and 8 GB model, as well as a new 80 GB hard-drive based model. They will be priced at $150, $200 and $250, respectively.

All three feature a new navigational interface called the Zune Pad, a touch sensitive button used for most commands on the device. Like the original 30 GB Zune, all allow users to share songs from device to device via its trademark WiFi feature.

However, Microsoft has eliminated two significant restrictions from the sharing capability. First, users can keep shared songs for as long as they want, not just three days as before. Each song, however, can still only be played three times before user must buy the copy. Secondly, users receiving shared tracks can now subsequently share them with other Zune users, something not possible in the first iteration.

Other new capabilities include an ability to wirelessly connect to the Zune service through the user's home WiFi network, but only when the device is plugged in. Additionally, users can now transfer and watch TV shows recorded on a Vista-based Media Center Edition PC on the Zune.

Microsoft also introduced new features to the Zune digital music service. Aside from an overhauled look and feel to the Zune Marketplace service, along with the addition of music videos, Microsoft unveiled plans to launch a Web-based social network called Zune Social.

Similar to other music-focused social networks like Last.fm or MOG, Zune Social will allow users create profiles (called Zune Cards) that will display their most recently played tracks, favorites list and so on -- similar to the Xbox 360 gamertag concept. Other members can then play samples of these songs, or download them when connected through the Zune Marketplace.

Artists can also create their own profiles, which will dynamically display the Zune Cards of other users who listen to that artist the most.

These "Zune Cards" are designed as a sort of widget, which Microsoft says users can eventually add to other sites like MySpace or Facebook, a blog, personal Web sites and virtually anywhere else a widget can be placed.

According to sources close to the situation, Microsoft will continue to pay Universal Music Group a portion of each Zune sale from the new devices, just like it has with the original Zune. There are no plans to discontinue the original 30 GB device, which Microsoft says has sold 1.2 million units to date.

That figure puts Microsoft well into the No. 2 position of hard-drive based MP3 players, behind Apple's iPod, which was the company's stated goal at launch. However, it hopes to achieve the same with the new flash-based devices, where SanDisk currently holds about a 10% market share, behind Apple's 74%.

The new devices and service elements are all scheduled to go live sometime in mid-November. Microsoft has not yet announced the specific date.