it would be great to be able to have the same source stream in MP3 and AAC+
and each one of those at 2 or 3 different bit rates.

Since iTunes does only mp3 and the iPhone can do AAC+ we have no way to have one stream in a 2 formats and 2 bitrates for iTunes and 3 bitrates for the iPhone.

streamtranscoderv3 is one option but it would be great to include something like this in Centova Cast that just works.

If you can recommend a console-based Linux streaming source that supports AAC+, we'll be all over it.

Currently sc_trans v2beta is the only option we're aware of, and it's a pretty ugly beast -- we'll be adding support for it once it's out of beta, but it eats a huge amount of RAM (100MB+ per process when we tested with beta3) and its CPU usage is even greater than that of sc_trans v1.

I wish to stream directly to AAC+, too. Please keep an eye out to add support for that at the earliest it is a viable option.

We have to use our Windows 2003 server to transcode to AAC / AAC+, as it can't be done presently in Linux.  

sc_trans v2beta is supported by the upcoming Centova Cast v3, which is currently in alpha testing.