I think the gap in achievement is a real concern, and needs addressing. It's something I've thought about a lot. (I'm a teacher, with August-born DD1 and June-born DD2!)
However, I don't think adjusting exam results is a good idea at all- you'll end up with employers and universities discriminating against summer-borns because their A* is worth less than an Autumn born individual.
I would like to see funding made available to support summer-borns and ensure they are reaching their potential- in the same way as the pupil premium. I also think teachers should be more aware of (and make allowances for) birth year. DD1 is in reception, and doing brilliantly 'academically' but we've had comments from the teacher about how she is easily distracted and doesn't always concentrate well. Well, yes- if she were 3 weeks younger, she'd still be at nursery.