At a recent event in Japan, Sigma representatives confirmed that the latest SD1 camera can do LiveView without a physical change to the camera:
"We can add the feature, however the hard part is to ensure that the camera operate in a stable manner with that addition. However, this is a high priority for us and we plan to take this on as soon as we finish working through some of the issues that we have pending right now. When and if we actually make this happen is up in the air at this point."
Sigma also confirmed that they are working on a new sensor without providing further details. There were some rumors in the past that Sigma is working on a full-frame version of the SD1 sensor. The SD1 DSLR camera doesn't not have video recording capabilities, but they may consider it in future models.