The Sony Ericsson X10 mini comes in a number of colours (just hit the gallery for the full range). However, if you were after the lime X10 mini and you’re in the UK, you’d better head to Orange as they will exclusively be stocking that colour.
It’s not on sale at the moment, but will be available on both Pay Monthly and Pay As You Go very soon. Not sure of the lime colour myself, much prefer the red and grey ones. Click through for a larger picture of the lime X10 mini.