Depends on what status you are adjusting from. If you're adjusting from visitor status, or K1 fiance(e) status, you shouldn't leave unless you have advanced parole first (you should have applied for AP with your AOS package).
If you entered the US on a K3 spouse status, then you are free to come and go as you please, for the 2 years validity of it.
If you entered with student status, or TN or other work related status, I'm not sure, but I think if the initial status is still valid, you can still come and go until the expiration date, but I'm not exactly sure. You may want to make an INFOPASS appointment at your local USCIS office to find out for sure, and/or to apply for Advance Parole (which will now be an additional fee, if you did not apply at the same time as your AOS)
INFOPASS appointments can only be booked on-line, on the USCIS website.
http://www.uscis.gov/portal/site/uscis Look down to the bottom right hand side "schedule an appointment"