In an interview at IGN Robert Orci confirmed that they are looking to fit Soundwave in Transformers 2.
Q: Is there one particular Transformer, good or bad, that you absolutely
had to get into the sequel?
ORCI: Yes.
Q: You're not gonna tell us.
ORCI: I'll tell you. We had to get Soundwave in there.
Q: Nice. Where Soundwave goes, will Ravage follow?
ORCI: Perhaps! Who's Ravage? ... I'm kidding! You know, we had Ravage in
an early draft of the first movie and Soundwave, and we couldn't do it right and
I think this time hopefully we'll have the ability to do it.
Of cause there is no word on an alt-mode for Soundwave as yet.