lilypad and the accelerometer don't have interfaces for sd memorycards. but you can look here Arduino Playground - SDMMC. anyway i never worked with sdcards so i have no detailed informations, all i know is that its possible ^^
there isn't a buildin powersupply in the accelerometer but accelerometers don't need that much power my ADXL330 runs on 2,0 V min and 3,6v max the lilypad needs 2.7-5.5 V you can run booth on the same powersupply as long its within range. or you can power the accelerometer from one of the digital outputpins.