Converting DisplayPort to 24 bit RGB parallel. Possible?
DisplayPort is very similar to HDMI, although I would consider it a higher-level communications standard than HDMI. This means it'd be more complex to convert a DisplayPort signal to a "raw" panel format, but it's certainly possible. To start with, you'll need either some kind of receiver IC, perhaps something along the lines of what ST or IDT offer (note EOL on second link) or, alternatively, you can make your own in an FPGA. If you go the latter route, there are several IP cores available, or you can roll your own. The receivers spit out LVTTL data which may or may not need additional translation or physical conversion to fit to your particular panel.

It's not a simple task, there is a lot of high frequency digital signalling flying around any board designed to do this, but it'd be a fun little project.

If you're looking for more of a kit and less of a build-your-own solution you could take a look at several vendors on ebay; a quick search found lots of items like this, but they are all HDMI or DVI or VGA to flat-panel, not DisplayPort. You could always contact them and see what they say, but I imagine they'll want to sell you a HDMI/DVI to flat panel board with a DisplayPort to DVI converter. :-/

Finally... a cautionary note: DisplayPort has its own version of HDCP called DPCP; you need to make sure that whatever you settle on handles that, or your video source may refuse to display anything even though your hardware is perfect. I didn't take a close enough look at ST's receivers but I know there are many HDMI receiver ICs that do have the option of internal HDCP controllers (along with a price increase, an NDA and other legal instruments)... that's probably your cheapest option if you must support DPCP.