I went in to get my transmission serviced today, and while I was there one of the tech'* was filling me in on a problem that he says happens to most of the SSEi'* at about 60k.
I just wanted to find out if there is any truth to this and if anyone has had the problem. Seems like there is a problem with the splines in the transmission and it strips because of to much torque. They said that the tranny has to be overhauled and runs a couple of grand. I don't know much about transmissions, so I don't know where the splines are located inside the transmission or what the part is called. Any idea'* or insight?

I'm not sure what splines they are speaking of but splines are located on shafts to hold them in sliding fits.
If I had to guess, I'd say the output shaft or input turbine shafts are prone to stripping and may be the limitation of the 280 ft-lb rating.
Check out the Transaxle section of this site.http://intense-racing.com/

I think your tech may be right.

I recently had to put a rebuilt transmission in my SSEi at 58K after the torque converter came apart. I did some research, and found out that there are apparently quite a few problems with the 4T65 transmission in the 2000+ SSEi.

The good news is that after I complained to Pontiac, they picked up the tab for the whole job.