I can't believe this just got me again but I figured out what the issue was: the phone was in "Debug" mode under Application-Development.  In addition to charging the phone and moving data to/from it, the usb is also used when developing Android apps.  I don't remember turning debugging on but once I turned off the debugging and restarted the phone, the usb worked fine (the little icon appeared in the top left of the screen).

FYI. This is the Google phone not Apple.

I did try wiggling the cable and even plugged it into several different ports but it didn't help.

This was definitely a software issue. Once I restarted the phone, it was fine.

Bob after much research on iphone problems, one that seems to come up is the data port pins in the phone not always getting good connection with USB cable on the or the cable it's self on the data end, any contamination in either can cause problems. These phones are made of micro parts and very sensitive to allot of the elements. It's kind of like a pot switch only it's open to dust and contamination.

They have replacement batteries out that are supposed to have a longer life than original batteries but that is what they say or advertise. I can not say for sure on that. But I think they have a bit higher mAh which I guess in theory would give it a longer run time, not so sure of longer life though. I can say this though, I bought a digital camera 7 years back and at the same time ordered a generic back up battery. The original that came with the camera Died about a year ago would not hold charge it was 1500 mAh the generic battery is rated at 2000 mAh and is still going. Apple is in the business of sales not shelf life.

Next time when you connect the data cable to your computer if the computer is not seeing the phone try slightly wiggling the USB cable on the data end or slide it in and out. See if that helps.

Not exactly sure why this happened but when I connected my myTouch 3G gphone running Android 2.2.1 to my Windows Vista machine, the little usb icon did not appear on the phone and the device did not show up on the computer.

After trying several reconnects and searching the Android menus but coming up empty, I tried powering down the phone and restarting it which solved the problem. 

The phone is about a year old and is starting show a decline in battery life to less than a day with almost no use (no calls, no bluetooth, no wifi) and has even shut itself off a couple of time because it was out of juice.  It's possible that it was in some weird state as a result of the low power issues but I'm not sure.