Before this happened to me I had never heard of this issue. Apparently it is a common one for Jeep LJ and TJ's. There are all sorts of posts in the forums about the automatic transmission shifter linkage breaking. Some would even suggest it should be a recall and fixed permanently by Jeep. It really isn't that big of a deal and can be fixed fairly easily and in just a few minutes if you have the right stuff.
Supplies for the quick fix:
2 Zip ties
Supplies for a more permanent fix:
2 Zip ties
1 Plastic bushing
First of all I want to say that you can fix the broken bushing on the transmission linkage with many different things... tape, string, chewing gum would even work in a bind. The fix that I think is the best solution is the zip ties. They are strong and can hold the linkage together for a long time if needed.
So the first thing you need to do is find where this part is on the underside of your Wrangler. It is on the driver side of the transmission. it is really close to the front drive shaft and is easily seen when you look at the space between the transmission and the driveshaft.
Next you will need to put the loop over the nipple and zip tie it on there there. It is as easy as that. I would leave the broken pieces in there to have a more secure fit but it really doesn't matter.
To add a bit more structure to the connection I bought some linkage bushings from the auto parts store and placed the right sized one in the looped end. Place the looped end over the nipple and then use the zip ties like before to secure them together.
I expect this will last a while like this. Perhaps indefinitely. There is another fix that involves replacing the nipple with a bolt and a nut to hold the loop on. There is another Jeep LJ or TJ website with this writeup.