This is what they say:
Out of an abundance of caution, Garmin has voluntarily chosen to globally recall its 2009 version of BlueChart g2 and g2 Vision data cards. In certain waters, there are inaccuracies and/or omissions in the way that this specific version of charting represents depth contours and depth areas, resulting in the depiction of water depth as deeper than the actual depth under certain display conditions.
Boaters should not use BlueChart g2 or g2 Vision 2009 data cards, dated March 2009, for navigation. Any boater who owns BlueChart g2 or g2 Vision v2009 will be given a replacement BlueChart g2 or g2 Vision card v2008.5 (dated July 2008) free of charge and will also receive the 2009 card free of charge when it is re-released.
Visit their web site and read more here:
We recently purchased a Humminbird GPS/ Chart Plotter which takes Navionic charts... Whew! So, this doesn't affect us, but thought we should pass this information on to other cruisers.