For a limited time you can purchase the Drupal 7 Unite theme for only $49! We have not set an end date on the sale, but don't miss out because it won't be on sale for long.
We have been working through our list of themes and have started the upgrade process to Drupal 7 on several others. We are still working through certain themes that use modules not upgraded to Drupal 7 yet, or those which only have upgraded Drupal 7 modules that are still in Beta or Dev status. We will keep a close eye on the module maintainer's updates to these modules used within some of our themes. Depending on the status of the modules within the upcoming weeks, we will determine how we want to proceed with Drupal 7 updates for those particular themes.
Some functionality loss may be seen, although we will keep each theme as feature-rich as possible and do not expect the loss of functionality to be major. Once we release each theme, we will notify customers of the Drupal 7 version and we'll also likely provide a sale or discount for each theme ported to Drupal 7.
I'll post more on the changes in Drupal 7 themes compared to their Drupal 6 counterpart within another blog post. There are some major differences in theming Drupal 7 from 6, so upgrading a Drupal 6 theme will surely bring about some caveats for customers.