I've made a pre-release build of Vienna 2.2 available on SourceForge for those who are interested. You can get the build from here:

http://sourceforge.net/project/showfiles.php?group_id=142635&package_id=157268&release_id=511708

The new version will work with your existing database and will upgrade it to the new format, but the upgraded database will continue to work with 2.1 if you choose to revert back. However as with all pre-release builds, keep in mind that bugs are inevitable and back up your database regularly.

The following is a list of changes in 2.2:

- Added ability to drop OPML files onto Vienna's dock icon.
- Added support for RSS/Atom enclosures.
- Add conditional support in templates.
- Overhauled UI.
- Added new standard style.
- Added more built-in styles.
- Command + T now opens new tab.
- Accept web pages as subscription URLs and parse to extract the feed.
- Show RSS button in browser if the web page links to an RSS feed. Clicking the button subscribes to that feed.
- New tab bar control. (Thanks to Evan Schoenberg).
- Add option to add Vienna to the system status bar.
- Added Basque localization. (Thanks to Aitor Zubizarreta).
- If Vienna doesn't handle the URL scheme (e.g., itms), open the URL with the default application for its scheme.
- Allow refreshing of unsubscribed feeds if they are specifically selected. (Thanks to ytrewq1 for submitting a patch.)
- Updated to SQLite 3.3.17.
- Change exported file format to UTF8. (Thanks to Kiyu Horiuti).
- Added toolbar and moved buttons to toolbar. (Thanks to David Kocher for the prototyping).
- Added support for toggle status bar and moved progress indicator to toolbar.
- Add toolbar button to empty the trash.
- Added flagged article filter.
- Refresh all subscriptions now refreshes in the folder list sorted order.

More changes are planned before we release however we welcome early feedback on the UI changes and other improvements. Please visit the support forum to post your feedback and reports:

http://forums.cocoaforge.com/viewforum.php?f=18

Thanks!