Yes, an individual that cashes checks for persons for greater than $1,000 in a single day is an MSB and would have to register as such. There is no requirement that an MSB be a entity.
For example, see the instructions for Box 9 on the MSB Registration FinCEN Form 107:
Item 9--EIN (entity), SSN/ITIN (individual). If the registrant is an entity enter its employer identification number (EIN). If the registrant is an individual and a U. S. Citizen or an alien with a social security number, enter his/her SSN. If the registrant is an individual who is an alien and has an individual taxpayer identification number, enter his/her ITIN. If a number has been applied for, but not yet received, leave item 9 blank. When the number is received file a corrected form.
First published on BankersOnline.com 2/04/08