freakasis wroteI am wondering if OpenVPN server has or can have the ability to limit login attempts and lock accounts/ip addresses down after a certain threshold?
This is not built into OpenVPN.
freakasis wroteIf this functionality is not built in, what would you suggest is the best way to go about implementing it?
On Linux (which you intend) this can be achieved via scripting. (The same could be done with windows batch file)
If you are concerned about hacking --
tls-auth offers a low level/immediate defence.
You would do well to consult the docs/howto/manual and user mailing list.