I read this Press Release, and the US Embassy in Cambodia is currently processing immigrant VISAs? Does this mean that I can file the I-130 form there, and have it processed immediately? Please, if anyone can verify this it will be great. If not, I will have to wait until their office is opened to find out.

I think that this refers to the fact that you can now have your petition processed and your interview in Cambodia. Until now, there was a " cambodian" section within the BKK US consulate. Due to the high threat/ bribe scenarios, Cambodians all had to process in Thailand. Although Im Australian I was living in Cambodia when I went through this process and was hoping to go through it there rather than go back to Oz. That was when I found out that even locals couldn't use the PP embassy. AS for DCF Im not sure....

There was another poster going through Cambodia, I think it was " appleegg" try his personal email, although he probably went through Thailand by now, he may be more up to date in the process.

No Consulates are able to accept I-130s at this time. When they are, the practice is generally reserved for US citizens living abroad.
Cambodia also has no USCIS Field Office.

If you are resident in the US, you should file in the US.