Amazon's not amazing at announcing useful timelines for their products/services. There are presumably a bunch of internal factors at play, but spending limits aren't the only thing that's been "in the works" for ages. If you're holding out for something that may or may not be coming (eg DevPay in your region, hard spending limits, long-term-queues, scheduling, ability to cloudfront s3 'subfolders' etc) it's frustrating, but on the other hand, they do tend to release well thought out services that make sense.

If it's any consolation, I have heard of individuals getting huge bills and having them cleared by Amazon when it became apparent that they hadn't willingly racked up that many fees (like the guy who included his S3 images in a google spreadsheet causing several TB of requests - http://www.behind-the-enemy-lines.com/2012/04/google-attack-... ).