I've been getting the same tingling sensation from my 2008 MBP. Here's what I've figured out...
When the MBP is plugged in using the ungrounded 2-prong plug, or if I'm just running on the battery, the MBP is has a "floating ground". In other words, earth ground=0 volts, but when not attached to earth ground, the MBP chassis is floating at a higher voltage compared to earth ground.
Electricity will always seek the path of least resistance to earth ground (or the closest thing to it). If you are using your grounded plug, then that ground line (the outside two gold pins on the magsafe connector are ground) will be the easiest path for the electricity to travel. The pins on my magsafe connector to the ground pin on the plug has around 1 ohm of resistance. The average human body has around 500 ohms of resistance. If you are using the ungrounded 2-prong plug, then you become the path of least resistance, hence the tingling sensation.
SOLUTIONS
1. Apple redesigns the MBP and eliminates this by "double insulating" it. Hmm... am I dreaming?
2. Use the grounded plug (keep in mind that this may not work if your outlet is not really grounded--that happens a lot.) An electrician should be able to help you with that one.
If you can't get connected to a good ground...
3. Wear rubber soled shoes when using your MBP (easiest solution.)
4. Keep your feet off of the floor. (You have to be sitting on something non-conductive to ground)
5. Keep a part of your body in contact with the MBP at all times... a grounding wrist strap connected to the MBP would work here, but that would be incredibly annoying. Additionally, you would still have that micro current going through you; but at least you won't notice it as much.
With all that said, has anyone experienced this phenomenon with the brand new MB and MBP?