MSP430-line part number decoding.  Derived from:

http://focus.ti.com/mcu/docs/mcugettingstarteddetail.tsp?sectionId=97&tabId=1511&familyId=342#decoder

Supplemented by analysis.

MSP 430 F G 4 6 19 S I QZW R
-+- -+- + + + + -+ + + -+- +
 |   |  | | | |  | | |  |  |
 |   |  | | | |  | | |  |  + Optional: Distribution format
 |   |  | | | |  | | |  |    R = Tape & Reel
 |   |  | | | |  | | |  |   
 |   |  | | | |  | | |  +--- Package
 |   |  | | | |  | | |     
 |   |  | | | |  | | +------ Optional: Temperature range (C)
 |   |  | | | |  | |         I = -40 to 85
 |   |  | | | |  | |         T = -40 to 105
 |   |  | | | |  | |                           
 |   |  | | | |  | +-------- (UNDOCUMENTED) Packaging variant MSP430x31x
 |   |  | | | |  |           S = 48-pin SSOP (vs standard 56-pin SSOP)
 |   |  | | | |  |
 |   |  | | | |  +---------- Family (memory size and peripheral configuration)
 |   |  | | | |
 |   |  | | | +------------- Series of similar function
 |   |  | | |
 |   |  | | +--------------- Generation
 |   |  | |                  1 = 1xx
 |   |  | |                  2 = 2xx
 |   |  | |                  3 = 3xx
 |   |  | |                  4 = 4xx
 |   |  | |                  5 = 5xx
 |   |  | |                  6 = 6xx
 |   |  | |                  0 = Undocumented (custom chip? MSP430C091)
 |   |  | |
 |   |  | +----------------- Optional: End-equipment optimized
 |   |  |                    G = Medical
 |   |  |                    E = Energy Meter (MSP430FE423)
 |   |  |                    W = Electronic Flow Meters (MSP430FW423)
 |   |  |
 |   |  +------------------- Memory Type
 |   |                       C = ROM
 |   |                       E = EPROM
 |   |                       F = FLASH
 |   |                       G = FLASH (Value Line device)
 |   |                       P = OTP
 |   |                       L = No non-volatile memory (MSP430L092)
 |   |
 |   +---------------------- 430 MCU Platform
 |
 +-------------------------- Processor Family
                             CC = ChipCon Radio
                             MSP = Mixed Signal Processor
                             XMS = Experimental Silicon

Non-conformant parts:

msp430bt5190 -- BT apparently denotes a part designed to work with the
CC2560 Bluetooth radio chip.  This is an msp430f5438 with the BT stack
already programmed in.
