Check the status match thread on this forum for details. I am CO Plat, and got DL to match me at Gold in August this year (DL will not match to Plat, so it's question for more research if they will match you Gold, or to Silver). It took about 2hrs from faxed letter to change in status noted online in my Skymiles acct.

One thing to note is that requests made in the first half of the year are honored only for the first half of that year. Requests made in the second half of the year are honored through the end of the entire following year.. So, for example, I was matched to DL Gold from August 2007 through Feb 2009. Unless the rules have changed, the same should hold true for you if you can pull this off today, Dec. 31. If it doesn't clear until Jan 2d, you may be DL Gold only until June 30, 2008.

My experience? Right after my matched status I boarded a DL flight JFK--> AMS, and was promptly op-uped to BE. Same thing happened on recent JFK-->DUB flight (and am hoping for the same on my return flight). ALL of my domestic segments, mostly transcon, have been upgraded, as a Gold (Take That! CO) I realize that my experience has been exceptional, so YMMV. And in any event the DL F and BE products are far inferior to CO, IMO.

Good luck