In regards to the timing of a battelfield 2142 demo, this site says:
Dice – The demo for BF2 went out about 10 days before launch if I remember correctly, I am sure something similar will be the deal for 2142. We are also going to throw out an open beta in the beginning of August. The beta is predominately to learn about large scale issues, i.e. when we have 10 000â€™s of people playing at the same time, eliminating some of the problems we have encountered after launch previously in the franchise. Keep your eyes open to join
So, since the US release is Oct 17th, we may see a demo on the 7th (probably 8th here in New Zealand).
Update: It has been confirmed that the demo should be available on gamespot at 5am Saturday New Zealand time.
I’ve got a LAN on tonight, so I expect that by the time I crawl out of bed tomorrow, you’ll have released your death-like grip on gamespot’s servers enough to allow me a download. Cheers.