
Without jailbreaking or messing around, it’s probably the best option. Native streaming will come with OSX in Mountain Lion. So it’s mac server > iOS client > airplay to ATV. Plex DOES support sreaming over airplay from an ios device, officially, with absolutely no jailbreaking. In a nutshell, the AppleTV is not designed to pull local content from anything other than an iTunes library, so anything else is going to be very hackish.

Recent betas of the Plex Media Server support DLNA streaming, but to my knowledge the AppleTV doesn’t support DLNA natively, so that’s a no-go as well. Plex does not support streaming via AirPlay it has it’s own client-server system, and the only AppleTV client I’m aware of is a jailbroken app since there isn’t official app support on the AppleTV. While you can use a jury-rigged setup (seriously - Drobo mount over Ethernet/WiFi to Plex Server over WiFi to an iOS device back over WiFi to the AppleTV - eek), it’s anything but straightforward.

I’m pretty sure you’re referring to Plex, not Plesk (at least, I couldn’t find anything like Plesk via Google).
