Cosmo posted a blurb about the new 2.5 Zune update; but I thought I would add a little more.

The new update has added some pretty good features. Some desperatly needed just to bring it up to date with other players, and some features that help set it apart from the rest. One thing Microsoft obviously trying to do is mimic the sucess of the Xbox 360's achievement system. While the Zune's 2.5 upate doesn't allow anything in the same ballpark as the 360's achievments, it does start to show some similarities. It will give users ratings, such as Top Listener, Bronze Power Listener, etc. What is also neat is that the Zune team has adopted the Xbox Live's Friends of Friends idea. Now, not only can you see the music stats of the people on your friends lists, but you can also see the friends of your friends stats. This may seem kind of useless on the surface, but if you are a music searcher like me, it makes for a fun time trying to find new music to download. You are able to go into each persons lists and listen to 30 clips of each song. Also new to the Zune Marketplace is user reviews. People can now review bands, or albums.

TV shows can now be downloaded from the Zune Marketplace. No longer are your videos tied to only your Xbox 360 (unless you download them through the 360). Now, you can download them directly onto your PC. You will be able to watch them on your PC, Zune, or stream them to your Xbox 360. And if you are clever enough, a quick search through google may allow you to gain total Fair Use of the files to play on any device ;-) Sadly though, movies are not yet downloadable onto your PC. You will still need to use your Xbox 360 for that service.But with iTunes recent movie service, I would not be surprised to see this come to the Zune marketplace soon.

The Zune software has also gained a much needed upgrade to its music tag editor. But, not only do you now have full metadata edit rights for your music, you can also edit tags of all of your video files. Also, there is now gapless playback and friends list built into the Zune software.

Since most users here at AGE do not own Zunes, this update may not exactly be any thing exciting. But, one thing to notice is the continued integration of the Zune and Xbox services. Both are stating to use more of each others features, blending them almost into one unified service. It may seem to be a slow process, but remember, the Zune services are only 1.5 years old. It is pretty amazing what Microsoft has been able to accomplish in this short of time. It's nice to see the two services slowly merging and becoming one, making for a better user experience for Zune and Xbox 360 owners.

[update]
I forgot to mention the new software also prepared the Zune platform for XNA gaming (thanks TazmanAK)
Also,  another note I just found when messing around with th enew update ... the friends of friends feature is infinite. I wish they would allow this for the Xbox 360. That would allow us to have some huge friends lists.