I have version 3.0.5 installed.
After clicking on "Run Now" a message appears on the top on the screen indicating that the job has started but no backup file or log record ever appears.
The scheduling page seems to be running on GMT. I'm on US mountain time (MST) and I can't schedule a job to run in the next 5 minutes. The closet time I can schedule a job to run is 7 hours in the future, which happens to be the time difference between GMT and MST. This problem didn't seem to happen in 3.0.4. I have the blog timezone set to MST.
The last backup I was able to run was on version 3.0.4. The wp_includes folder wasn't included in the backup file. I noticed 3.0.5 was available so upgraded wondering if it was a bug in 3.0.4. I haven't been able to run a test backup since because of the apparent timezone issue.