First, I love the new version of WordPress; it's going swimmingly, aside from one small issue that I'd like to report. (I've created a Trac ticket, but thought I'd post it here too just in case someone has any other insights.)
I password protect my wp-admin directory using standard HTTP auth for an added level of security. I love the new media uploader included with WordPress 2.5, but it fails for the first upload in each session, possibly because of this password protection.
Here's how the problem manifests itself:
When I select a file with the new media uploader, a small dialog appears, prompting me for the username and password. I enter this information and press OK. Everything appears to have worked normally, but then it turns out that the file was not successfully uploaded. WordPress will behave as if it had worked (showing a blank image in the media browser, along with the relevant title and description information), however, the actual image file will not be there.
The solution is to do delete the half-created media entry, and upload the media a second time, now that the username and password had been previously entered. This will work for all subsequent uploads until the next session.
It's only an annoyance right now, but it would be nice to not have to go through the process of uploading everything twice when I write a post. If anyone has any ideas or insights, I'd much appreciate it. Thanks!