I have this case and I've verified the magnet has no affect on the handset.
http://cgi.ebay.com/HTC-IMAGIO-VERIZ...item5ad43ce1da
Unfortunately, because it is pretty tight, one of the buttons on the bottom can sometimes be depressed by the side of the case while putting in/pulling out. Also, as you move about with the case on your belt, this could put pressure on the buttons and possibly depress one. I haven't noticed this happening consistently, but I'm sure it can/will happen. This would turn the screen on, of course, but doesn't unlock it. I normally use the Verizon holster, but I use the case when I need extra retention security (such as when I'm on my motorcycle). I suppose I'll live with this and hope someone comes up with a mod. I think something like a long push on a volume key would be better.