The busiest single period of the app marketing year is going on right now — and yesterday, on Christmas, all eyes were on the iTunes App Store. Fiksu was carefully monitoring the App Store, watching for the “freeze” — the period where ranks in the all-important Top Charts stop moving. In recent years, the freeze has been getting shorter and shorter. This year, for the first time, there was no real freeze at all. As we discussed in a recent article on VentureBeat, a change to how the App Store updates made a potential freeze largely irrelevant anyway: because ranks only update every three hours, there’s…..