After reading all the posts in this thread, I am almost convinced this is a hardware problem, caused by corrosion on the contacts of the home switch. This is very common, and happens to nearly all electrical contact switches over time. Cleaning the contacts removes the conductive coating, and will only make the problem come back later.If you open the unit, do not use any abrasive tools to clean the contacts - instead use an industrial contact cleaner spray or liquid. (in fact, you might even try spraying some in through the charging port, without opening the unit up)
The fact that blowing the charging port seems to fix the problem, albeit temporarily, indicates that the moisture in your breath is temporarily breaking down the corrosion. Pluging in the phone also seems to temporarily fix the problem, probably because you are disrupting the corrosion (same effect as slapping the back of the phone) - but eventually, the problem will return. The fact that plugging it into iTunes seems to fix it is a false positive - I would suspect that plugging it into any power source to charge it will most probably have the same effect - or just plugging and unplugging the power cord several times.
It would be interesting to see what parts of the country users are experiencing this problem.. I would suspect if you are living in a hot dry climate, it is more unlikely than if you are in a humid climate or live near the sea where there is a lot of salt content in the moist air.
Personally, I always wondered why Apple never provided a 'cover plug' to close off the power port when not in use. Over time, this is just going to collect crud from your pocket or purse. Closing the port when not charging or connected to iTunes seems like a logical preventitive step.. Even cheap flip phones have plugs closing off the open ports.
