I went to the Apple store in Greenville, SC today and picked up the 13" i5 128 MBA. I got a really helpful employee who knew about the SSD issue, and said he was getting an 11" soon and was going to make sure he got a Samsung with his. He seemed willing to go through as many MBAs as necessary for me. The first one he got out had the Toshiba, and while he went to the back to get another, I checked all the floor model MBAs and interestingly every 11" but 1 had a Toshiba and every 13" had a Samsung. He told me that he went to the very back of the stock (where the newest would be) and picked out the last one. Sure enough, it had a Samsung! I didn't care too much about the display but I checked it when I got home and it's the LG. Hopefully all the newer stock in Apple stores are Samsung SSDs.
As far as I know, the only way to tell which SSD is installed is to open the box, boot the machine and check the system information. Did the employee open all of those boxes for you, or did he have some other way of identifying the SSD? Checking serial numbers or some such? I'm just curious because every post that I've read here says that the only way to know is to open the box, and I'd be amazed if an employee did that.