Metabolix, Cambridge, Mass., announced last month that Target had rolled out biodegradable gift cards to all of its stores in time for the holiday season. In July, Target began testing the gift cards in 129 stores before introducing them chainwide. The gift cards are made using Mirel, a bio-based plastic from Metabolix. Unlike the petroleum-based plastics that have traditionally been used for cards, Mirel will biodegrade in environments such as soil, home compost, wet-lands, rivers and oceans.