WordPress 2.8.1修改了一些BUG，如某些主题用get_categories()依然有效；升级失败时也不会删掉一些文件；编辑器问题；安全问题等。

We’ve started work on the first maintenance release to 2.8.  2.8.1 will fix a handful of bugs that turned up in 2.8.  Today we’re releasing the first beta of 2.8.1.  Download it, and check out the bugs fixed so far.  Here are some of the notable issues that are fixed in beta 1.

• Certain themes were calling get_categories() in such a way that it would fail in 2.8. 2.8.1 works around this so these themes won’t have to change.
• Dashboard memory usage is reduced.  Some people were running out of memory when loading the dashboard, resulting in an incomplete page.
• The automatic upgrade no longer accidentally deletes files when cleaning up from a failed upgrade.
• A problem where the rich text editor wasn’t being loaded due to compression issues has been worked around.
• Extra security has been put in place to better protect you from plugins that do not do explicit permission checks.

If you would like to automatically upgrade from 2.8 to 2.8.1 Beta 1, follow these instructions.  Thanks for testing WordPress.

http://wordpress.org/development/2009/06/wordpress-2-8-1-beta-1/