Charging issues experienced by owners of older MacBook and MacBook Pro models when using the new L-shaped MagSafe power adapters have been solved via a firmware update from Apple.
The MacBook SMC firmware update 1.4 is available for qualifying MacBook models via Software Update or directly from Apple, here.
Keep in mind that installing an SMC firmware update is different than other updates. Your battery must have at least a 25 percent charge and you must be plugged in to a power source. You must start your Mac to Mac OS X 10.5.8 or Mac OS X 10.6.4.
When your computer restarts, a gray screen will appear with a status bar to indicate the progress of the update. Your computer's fans may run at full speed during the update but should return to normal speed once the update completes. Do not disturb or shut off the power on your computer during this update.