Hi, I just got the notice about removal of condition as well. In my letter, they asked me to go to local service office to get a new alien registration receipt card (form I-551), also bring passport and 3 recent photos. And the new card will be mailed to me within 6 months.
If you have more questions, you can call 1 800 375 5283 (INS number), you need to hold for long time though to speak to an immigration specialist.
Hope this is helpful.