I emailed channel 4 labout 2 weeks ago & channel 4 emailed me back & said it wouldn't be till next year.You don't have to be Sherlock Homes to work that out.
This year they showed season 2 in May so i'm guessing it might be the same for season 3.In saying that it depends in the contract ch4 have with ABC(The station that shows it in the States).Even though ch4 have the rites to the series i'd guess ABC would have some say when ch4 can show it.
For example Season 3 will be shown on the 4th October for 6 weeks then it breaks for christmas & the remaing episodes will not be shown till 2007.I can't see ch4 showing the episodes anytime then.