Matt Griffin has written a great blog post, so I’m just going to echo it:

After over a year’s worth of feedback from users like you and a clear view of where we want to take Ubuntu One in the future, we’ve just made some changes to the Ubuntu One service offering and pricing plans.

For starters, we will no longer offer the 50 GB plan to new subscribers. Everyone will get the basic plan and then have the option to add various ‘add-ons’ of services and storage as needed. But here are the details:

Ubuntu One Basic – available now
This is the same as the current free 2 GB option but with a new name. Users can continue to sync files, contacts, bookmarks and notes for free as part of our basic service and access the integrated Ubuntu One Music Store. We are also extending our platform support to include a Windows client, which will be available in Beta very soon.

Ubuntu One Mobile – available October 7th
Ubuntu One Mobile is our first example of a service that helps you do more with the content stored in your personal cloud. With Ubuntu One Mobile’s main feature – mobile music streaming – users can listen to any MP3 songs in their personal cloud (any owned MP3s, not just those purchased from the Ubuntu One Music Store) using our custom developed apps for iPhone and Android (coming soon to their respective marketplaces). These will be open source and available from Launchpad. Ubuntu One Mobile will also include the mobile contacts sync feature that was launched in Beta for the 10.04 release.

Ubuntu One Mobile is available for $3.99 (USD) per month or $39.99 (USD) per year. Users interested in this add-on can try the service free for 30 days. Ubuntu One Mobile will be the perfect companion to your morning exercise, daily commute, and weekend at the beach – we’re really excited to bring you this service!

Ubuntu One 20-Packs – available now
A 20-Pack is 20 GB of storage for files, contacts, notes, and bookmarks. Users will be able to add multiple 20-Packs at $2.99 (USD) per month or $29.99 (USD) per year each. If you start with Ubuntu One Basic (2 GB) and add 1 20-Pack (20 GB), you will have 22 GB of storage.

All add-ons are available for purchase in multiple currencies – USD, EUR and, recently added, GBP.

Users currently paying for the old 50 GB plan (including mobile contacts sync) can either keep their existing service or switch to the new plans structure to get more value from Ubuntu One at a lower price.

We know that you will enjoy these new add-ons as well as the performance enhancements we’ve made to Ubuntu One in recent months. If you have questions, our recently updated support area is a great place to start. There you’ll find a link to the current status of Ubuntu One services, a link to our frequently updated list of frequently asked questions, and a way to send us a direct message. As always, you can also ping the team on IRC (#ubuntuone in freenode). We welcome your questions, comments and suggestions.