I need a new shingle roof, does the 12/2 minimum pitch still apply if I use peel-n-stick?
If there are not asphalt shingles and  it meets the manufacturer specs for install, I can't find why not but you may still need to get it approved.

All from Florida Building Code 2004


  CHAPTER 9: ROOF ASSEMBLIES
  
  SECTION R905 REQUIREMENTS FOR ROOF COVERINGS
  
  R905.1 Roof covering applications. Roof coverings shall be applied in accordance with  the applicable provisions of this section and the
  manufacturer’s installation instructions.
  
  R905.2 Asphalt shingles. The installation of asphalt shingles shall comply with the  provisions of this section.
  
  R905.2.1 Sheathing requirements. Asphalt shingles shall be fastened to solidly sheathed decks.
  
  R905.2.2 Slope. Asphalt shingles shall only be used on roof slopes of two units vertical in 12 units horizontal (2:12) or greater. For
  roof slopes from two units vertical in 12 units horizontal (2:12) up
  to four units vertical in 12 units horizontal (4:12), double
  underlayment application is required in accordance with Section
  R905.2.7.
  
  R905.2.3 Underlayment.  Unless otherwise noted, required underlayment shall conform to ASTM D 226 Type I, ASTM D 4869 Type I,
  or ASTM D 6757. Self-adhering polymer modified bitumen sheet shall
  comply with ASTM D 1970.
  
  R905.2.7 Underlayment application.  For roof slopes from two
  units vertical in 12 units horizontal (17-percent slope), up to four
  units vertical in 12 units horizontal (33-percent slope), underlayment
  shall be two layers applied in the following manner. Apply a 19-inch
  (483 mm) strip of underlayment felt parallel to and starting at the
  eaves, fastened sufficiently to hold in place. Starting at the eave,
  apply 36-inch-wide (914 mm) sheets of underlayment, overlapping
  successive sheets 19 inches (483 mm), and fastened sufficiently to
  hold in place. Distortions in the underlayment shall not interfere
  with the ability of the shingles to seal. For roof slopes of four
  units vertical in 12 units horizontal (33-percent slope) or greater,
  underlayment shall be one layer applied in the following manner.
  Underlayment shall be applied shingle fashion, parallel to and
  starting from the eave and lapped 2 inches (51 mm), fastened
  sufficiently to hold in place. Distortions in the underlayment shall
  not interfere with the ability of the shingles to seal. End laps shall
  be offset by 6 feet (1829 mm).
  
  CHAPTER 1 ADMINISTRATION
  
  SECTION 104 DUTIES AND POWERS OF BUILDING OFFICIAL
  
  104.11 Alternative materials, design and methods of construction and equipment.  The provisions of this code are not intended to prevent
  the installation of any material or  to prohibit any design or method
  of construction not specifically prescribed by this code,  provided
  that any such alternative has been approved. An alternative material,
  design or  method of construction shall be approved where the building
  official finds that the  proposed design is satisfactory and complies
  with the intent of the provisions of this  code, and that the
  material, method or work offered is, for the purpose intended, at
  least  the equivalent of that prescribed in this code in quality,
  strength, effectiveness, fire  resistance, durability and safety. When
  alternate life safety systems are designed, the 
  SFPE Engineering Guide to Performance-Based Fire Protection Analysis and Design of  Buildings, or other methods approved by the building
  official may be used. The building  official shall require that
  sufficient evidence or proof be submitted to substantiate any  claim
  made regarding the alternative.


Note: Also be aware of local amendments and declaratory statements