I have filled in all the amazon details and made my "/s3temp" directory writeable as requested, the plugin says it is active (i.e. no complaints about its setup).
Cron appears to firing off (here is an example of the every 5 minute schedule):
Jul 9, 2010 @ 15:37 (1278689840) S3 Cron Schedule s3CronHook
But no files are being uploaded into my bucket (e.g. static.mydomain.com)
Any ideas what I could look at to investigate further?