UA revealed that they are going to drop a second daily flight to EWR from MAN and DUB and replace it with a flight to IAD, so still 2 flights in the summer, with one to EWR and one to IAD.
There was no mention of EDI or Scotland at all in this press release, which makes me think they have no interest in another route from EDI. I do hope they bring back the CO109 (or some incarnation of it) but as others say, it still isn't available to book even though the CO37 is there well into summer 2012.
United Continental Holdings, Inc. - Investor Relations - News