First of a series of updates.
New PROJ 4.6. Note that there is a change in behavior in the datum transforms (I believe you must be very explicit now) – see the PROJ mailing list archives for discussion about this change.
Independent of this update, there was a bug introduced in the Leopard PROJ NAD transform functions. Due to the method used to generated the NAD files at compile-time, there was an error reading them on 32bit Leopard, and NAD transforms would be incorrect. Fixed.