Amazon's S3 storage solution crashed earlier today, causing widespread issues with a range of web 2.0 applications. The service is popular among startups due to its cheap pricing and usual reliability.
Allen Stern broke the news on Centernetworks, noting that the service went down at around midday US EDT. His latest update indicates (per the screenshot above) that some 6 hours later the service was slowly coming back up. Affected services include the iPhone Twitter client Twinkle and photo hosting service SmugMug. Other services affected include the AIR Twitter client Twhirl, which relies on S3 for avatar hosting.
WebWorker Daily notes that Amazon offers a 99.99% uptime guarantee on S3, which equates to no more than 45 minutes of downtime a month, with refunds available for longer downtime.
For those affected by the downtime, the Amazon status page can be followed here.
Update: outage seems to have take Plurk completely offline as well.