we currently don't have a release date for a new build of LinuxICE. We are starting from scratch (codenamed LinuxICE2) with the latest hardware in mind (atom based hardware, as well as C7 and via Nano's).
I've written code to toggle DTR in the past for Linux. I suppose if it was a feature that a number of people wanted, we could definitely add it as an option.
We are getting pretty close to having the core finished. We'll keep the forums updated as more progress is made.