The vMA came out first, and was generally the focus of VMware's management training.
Then PowerCLI came out, and everything was PowerCLI focused. As an example, my VCP4 was heavily vMA oriented, my VCP5 never discussed it.I'm not aware of anything official regarding depreciating vMA, but I wouldn't be surprised if it happened. One of the major functions of the vMA, the log collector, was easily replaced by the syslog collector being bundled with vCenter.
The vCLI is effectively a locally installed toolset based on the vMA.
In short, if you have just started, I would recommend concentrating on PowerCLI.
