The new plan will be $1 a day on days you use your phone. What you get for that dollar is unlimited nights (no weekends) starting at 7 p.m. (better than INPulse's 9 p.m.) and mobile-to-mobile (similar to GoPhone and Verizon, just with a smaller mobile-to-mobile base by about 60%). Anytime minutes that aren't to T-Mobile customers will run you 10 cents apiece. Text messaging pricing won't change...I believe it's 10 cents to send a message and 5 cents to receive at the moment.
The new phones are the Nokia 1208, a very basic bar phone, and the Nokia 2760, a rather low-end cameraphone flip. I'm sure they'll be inexpensive and I'll probably even take the 2760 over the Alcatel Oxygen Wireless will be rolling out soon. Then again, neither phone is impressive, unless the 1208 is free with an airtime card and all you do is talk, with a text or two mixed in.
I don't think T-Mobile will discontinue their old (good) prepaid plan, and I hope they don't. This is no replacement for a regular prepaid plan but it's a definite addition to their lineup, and more hybrid variety is always good!