The typical etiquette is to do it the other way around, some are invited to both, others are invited to the reception only. This is usually done in instances where space is limited for the ceremony.
Not inviting friends and acquaintences to the reception is considered "cheap" and a grab at gifts without actually inviting them to celebrate your marriage.
Check out the Etiquette Hell forums - they usually debate the pros and cons of various etiquette rules. This thread may explain my thinking:
http://www.etiquettehell.com/smf/ind...?topic=79165.0