Under the current TAG program are public deposits held by an institution in a non-interest bearing account eligible for unlimited coverage? If the same public entity maintains a separate MMA which is limited to $250k before pledging is would the two accounts added together (same public ID#) fall under the $250k limitation or can they be treated independently?

See the footnote in the linked pdf.
1 From the period from December 31, 2010, through December 31, 2012 the Dodd-Frank Wall Street Reform and Consumer Protection Act (Dodd-Frank Act) provides separate and unlimited deposit insurance coverage for accounts that meet the definition of ‘noninterest-bearing transaction account.’ This unlimited coverage for such accounts is separate from the $250,000 coverage provided for other types of accounts.

PDPA Insurance Information

See the following information from the FDIC:

In the new "Permanant Rule":

...The insurance coverage of public unit accounts depends upon the type of deposit and the location of the insured depository institution. All time and savings deposits owned by a public unit and held by the same official custodian in an insured depository institution within the State in which the public unit is located are added together and insured up to $250,000.

Separately, all demand deposits owned by a public unit and held by the same official custodian in an insured depository institution within the State in which the public unit is located are added together and insured up to $250,000....

http://www.fdic.gov/deposit/deposits/FactSheet.html