Ah, I just made this decision! I decided to go for a T42 (again - I'm hoping that the new one that's coming doesn't have the problems that my last one did) over a Z60t for a few - mostly superficial - reasons. The shipping time for the T42 will probably be less, and I prefer the materials used in the T-series to those used in the Z - although there's nothing wrong with CFRP, I have to believe that it's just better when reinforced with titanium, and the magnesium screen lid might be better. I was also put off by the fact that the Z60t has a fan intake on the bottom, while the T42 had... some other way of drawing air into the laptop, which seems more difficult to block. Another bonus of the T42 was that the standard 6-cell doesn't stick out, and there's an option to go up to 9 cells, while the standard battery for the Z60t is a wimpy 4-cell, and the 7-cell battery sticks out. Finally, I thought the Z60t was just ugly in comparison to the T42.
Of course, the Z60t has a lot of advantages to consider. Personally, I think it actually represents a slightly better deal than the T-series, but not a big one.