We use the S3 plugin in both a newer Jenkins install (v1.471, waiting for some important stuff to clear before we update it to 1.474) and a few older Hudson builds. The current Jenkins w/S3 (v0.3) works for a while, then all our builds stop uploading to S3 with an "Access Denied" error from Amazon. The builds on the older Hudson/S3 still work to the same bucket, and our credentials still work when I test with s3fs on the same machine. Error from Jenkins build console of one failure (buckets and filenames changed to xxxxx):

Archiving artifacts
Publish artifacts to S3 Bucket Using S3 profile: builds2
Publish artifacts to S3 Bucket bucket=xxxxxxx/store, file=xxxxxxx.latest.apk
ERROR: Failed to upload files
java.io.IOException: put Destination [bucketName=xxxxxxxxx, objectName=xxxxxxx/store/xxxxxxxxxxx.latest.apk]: Status Code: 403, AWS Request ID: 85F9CB0156BF7CF6, AWS Error Code: AccessDenied, AWS Error Message: Access Denied, S3 Extended Request ID: swP7ylP4SQNW3o9uP3alhBO/VZthqvuFxWiZ2Pn54mqhSHk2uEtSrIlhPXlJLPUM
at hudson.plugins.s3.S3Profile.upload(S3Profile.java:82)
at hudson.plugins.s3.S3BucketPublisher.perform(S3BucketPublisher.java:119)
at hudson.tasks.BuildStepMonitor$2.perform(BuildStepMonitor.java:27)
at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:717)
at hudson.model.AbstractBuild$AbstractBuildExecution.performAllBuildSteps(AbstractBuild.java:692)
at hudson.model.Build$BuildExecution.post2(Build.java:183)
at hudson.model.AbstractBuild$AbstractBuildExecution.post(AbstractBuild.java:639)
at hudson.model.Run.execute(Run.java:1509)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:46)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:236)
Build step 'Publish artifacts to S3 Bucket' changed build result to UNSTABLE