Before anyone brings it up, no, I don't know anything more than anyone else. I found out about this change via Twitter this afternoon, the same as everyone else.

That being said, please read the announcement "straight from the horse's mouth" at http://blog.comcast.com/2012/05/comcast-to-replace-usage-cap-with-improved-data-usage-management-approaches.html

In that article it states, as Twinsfan hopes:

The first new approach will offer multi-tier usage allowances that incrementally increase usage allotments for each tier of high-speed data service from the current threshold. Thus, we'd start with a 300 GB usage allotment for our Internet Essentials, Economy, and Performance Tiers, and then we would have increasing data allotments for each successive tier of high speed data service (e.g., Blast and Extreme). The very few customers who use more data at each tier can buy additional gigabytes in increments/blocks (e.g., $10 for 50 GB).

The second new approach will increase our data usage thresholds for all tiers to 300 GB per month and also offer additional gigabytes in increments/blocks (e.g., $10 per 50 GB).

If I learn more via official channels I will of course share with you all. Personally, I don't even come close to hitting 250GB. Looking back at my router's WAN traffic logs the most I've used is around 150GB and I wasn't consciously trying to stay below any kind of limits. Also worth noting, these caps have only ever been on residential accounts. Business Class accounts have no such limits.