Familiarity may have something to do with it, but I don't think it's the main reason I've seen 4E combat take so much longer. The 4E games involved people very familiar with the system, and some of the Pathfinder games had one person new to the system, with the rest being very familiar with it.
And yet... and yet, my experience is the complete opposite. My first 4e experience was with a new DM (not only new to 4e, but had never DM'd anything before) two brand new 4e players (myself and one other) and two experienced 4e players.
We played the Rivenroar module. Combats took about 40 minutes each.
By what you are saying, we should have been taking hours to play through.
Never minding the WOTC podcasts themselves, all of which showing combats taking around 40 minutes as well.
Hey, in 3e, by the end of things, we had our combats down to about 40 minutes as well, most of the time. Until we hit double digit levels, and then combats went from 3 or 4 per session to one.
Now, I do play in another 4e game as a player. There, combats have taken up to two hours. But, that's not system, that's player problem. The same group was glacially slow in 3e as well.
I find it very hard to understand how anyone could blast through 3e combats in under an hour and then see their time double in 4e. 4e is easier than 3e. There's no grapple rules, AOO's are considerably more simplified and you have far less standard options like trip or disarm to grind the game to a halt.
What are you doing in 4e that takes you so much longer than 3e?