Prior to current military operation, was Israel occupying Gaza as Hamas claims? What's your guess?

I don't have connections to either Israel or Palestinians, but I'm fascinated by the intricacy of the conflict and by the propaganda. 

For example, Hamas and all their allies--including the American media--constantly refer to Israel as "occupiers"--though in the case of U.S. media this is typically in the form of quoting Palestinian spokesmen without offering any kind of rebuttal.

Both the accusation and the way it's tacitly supported by U.S. media are brilliant.  I suspect that if you asked Americans whether Israel was occupying the Gaza strip (before the current military action), about 80 percent would agree.  (The same 80 percent who believe Obama has presented a genuine long-form birth certificate for examination.)

But in fact, Israel voluntarily withdrew all Israelis and IDF forces from Gaza in August of 2005.  This withdrawal included removing Israeli settlers from 21 settlements in Gaza.

Yep, the government of Israel offered Israelis who had settled in the strip compensation for their homes and property.  Those who refused the offer were forcibly removed by Israeli soldiers.

I remember being really surprised when the withdrawal was announced.  For one thing, military analysts predicted that removing all IDF troops from the strip would enable Gaza residents to fire rockets into Israel--a prediction that certainly turned out to be accurate.

Amazingly, Palestinian reaction to the plan was mixed, with some denouncing it as not going far enough because it didn't include withdrawal from the West Bank.  Some people will always find something to bitch about.