I just got this back from the State Attorney General's office 
regarding entry fees for photo contests;  They write:

Please be advised that we have been in touch with Audobon Magazine as 
well as the State Lottery Commission.  The State Lottery Commission 
has advised that it does not believe that there are any prohibitions 
under the laws it regulates to prevent the magazine from opening its 
contest to Maryland citizens despite the fact that a fee is charged. 
The type of contest described is also exempt from the Maryland laws 
that this office regulates, as it is considered a game of skill.  As 
such, the Audobon Magazine would not be prevented from offering this 
contest to Maryland citizens as a result of charging a fee.

In addition, we have been contacted by other persons about this same 
issue and we have advised that each person should file a complaint 
with our office that would allow us to formally notify the Society as 
well, but to date, I don't believe we have received a formal 
complaint.  In the meantime, you should print this email and provide 
this with your submission to notify the magazine that we do not 
believe that their exclusion of Maryland is based on a correct 
understanding of Maryland law.  It is our hope that with this 
information, they will accept your submission.
-- 
Melanie Lynch
Annapolis