In Windows 7 I resolved this by modifying my Windows system settings to use the Windows Black (system scheme). The caret I-Beam shape is surrounded by a white stroke that stands out over dark backgrounds and invisible over pure white backgrounds.
Go to Control Panel–>Appearance–>Ease of Access–>Make the mouse easier to use
and choose “Regular Black”
You would think that that the Inverted option would work, but the color remains black over the dark greys of the VS 2012 dark theme. The Regular Black does work well though.