@nucleon: True, but he wasn't too far away from him in terms of speed and got close to tagging him. Do you see Thor replicating that feat like Superman did?
No, he can't of course, but there's no need to neither if Thor simply calls down lightning on him or if he effectuates an area-of-effect attack (by striking the ground). He could also just throw the hammer at him, although his motion won't be fast enough.
Thor doesn't have to solve problems "à la Superman"; He is his own character, and can arrive to Superman's results, or better, using another manner entirely - and vice-versa.
I agree that Thor may be able to tag Flash through other means, and I wasn't arguing against that. A user made a claim that Thor could do everything Superman did in the movies, and that was one instance that I couldn't see Thor replicating and wanted to point out.