Saw an article on tweetcall yesterday – looks twitterfone-like in functionality. And feedback from various people since I tweeted about it suggests it all works well. Nice simple site design too (must have permission from Twitter for that name and styling, right?? 🙂
Anyway – worth a look – it’s powered by Quicktate – the people who do the voicemail to text service (like SpinVox or PhoneTag).