I know that AG-HMC152 is the PAL version of AG-HMC150, which is the NTSC version. But, now - I hear of another variant - AG-HMC151. What is 151 then?

None of them are PAL or NTSC. All these cameras only record high definition formats, and PAL and NTSC only have a meaning for standard definition, and strictly speaking only for composite standard definition, not component.

The 150 will only do HD formats based on 24, 30 and 60 fps and are intended for countries with 60Hz mains frequencies. The 151 (which is what's available in the UK) is swichable between those and 25 and 50fps based HD formats.

Thanks ... Looks to me that the 152 is only 25 and 50 frames/sec. Can't switch to the US frame rates - in other words.