The latest T-Mobile US 2.02 ROM is itself called â€œRUU_Leo_1_5_TMOUS_2.02.531â€¦â€ which hints at something different, and within it there are a few references to Leo 1.5 or HD2 1.5.
Thinking about it though, there have been a few other 1.5 or 2.0 devices. The leaked 2009 set of handsets had the Sapphire, Sapphire 1.5 and Sapphire 2.0. I suspect the differences are related to the radio (so the 1.5 supports a different set of bands) rather than anything else.
One thing is for certain though, the Leo is coming to the US on T-Mobile, and it will be there soon.