Here's a database of all the interchanges RIDOT has changed over to LEDs:

Interstate 95 (Some LEDs):
Exit 1 - LED on new short poles
Exit 2 - LED on new short poles
Exit 3 - HPS, electric company-owned 250W HPS poles with individual photocells
Exit 4 - LED on new short poles
Truck Stop - LED on new short poles
Exit 5 - LED on existing short poles
Exit 6 - 250W HPS drop lens on short davit poles
Exit 6A (separate interchange from exit 6): LED on existing tall poles
Exit 7: 1000W MH highmasts
Exit 8 & 9: LED on existing short poles
Exit 10: LED on existing tall poles
Exit 11: 400W HPS M-400 FCOs on tall davits
Exit 12-30: various HPS; no LEDs between Exit 12 and the Massachusetts state line on I-95. This portion of I-95 is continuously lit.

Interstate 295 (Some LEDs):
Exit 1 & 2: 400W HPS M-400 FCOs on tall davits
Exit 3: Electric-company-owned 250W HPS truss poles and individual PCs (as opposed to RIDOT relay controls)
Exit 4: 400W HPS M-400 FCOs on tall davits
Exit 5: 250W HPS M-400 FCOs on short davits
Exit 6: 400W HPS M-400 FCOs on tall davits
Exit 7: LED on existing tall poles
Exit 8: 250W HPS M-250R2 drop lens on short RIDOT poles, individual PCs
Exit 9: 400W HPS drop lens on tall davits
Exit 10: Electric-company-owned 250W HPS truss poles and individual PCs (as opposed to RIDOT relay controls)
Exit 11: Electric-company-owned 250W HPS truss poles and individual PCs (as opposed to RIDOT relay controls)

Interstate 195 (No LEDs):
All lights on I-195 in Rhode Island are still currently HPS, either 250W drop lens or 400W FCO.

Route 4 (All LED):
All lights on RI State Route 4 have been changed to LEDs (5 interchanges).

Route 138 (Some LEDs):
Lights on the Jamestown and Newport Bridges have been LED'ed. The status of the actual freeway lighting is unknown at this time.

Route 403 (All LED):
All lights on RI State Route 403 have been changed to LEDs (4 interchanges).

Theodore Francis Green Airport Connector Highway (No LEDs):
All lights on this short little highway, connecting I-95 to T.F. Green Airport, are still 250W HPS drop lens with individual PCs.

Route 37 (No LEDs):
Exit 1: Electric-company-owned 250W HPS truss poles and individual PCs (as opposed to RIDOT relay controls)
Exits 2-3: 400W HPS drop lens on tall davit poles, relay controlled.
Exit 4: 250W HPS drop lens on short davit poles, PC-controlled.
Exit 5: Same as Exits 2-3.

Route 10 (Some LEDs):
Freeway lighting at the Reservoir Avenue interchange have been changed to LEDs on new short davits. All other lights are HPS, some RIDOT-owned and others owned by the electric company.

Route 6 (Some LEDs):
Freeway lighting on US Rte 6 is LED on new tall poles between Hartford Avenue and Magnolia street, but is HPS (400W HPS on tall davit poles) everywhere else on the freeway. The LEDs were a result of the freeway being reconstructed at that portion.

Route 146 (No LEDs):
All lights are still HPS. Some short 250W HPS RIDOT lights, lots of tall 400W HPS RIDOT lights, and some 250W HPS electric company-owned lights.

Route 24 (Some LEDs:
I think all lights are LED but I cannot confirm this. The Sakonnet (suh-KON-it) River Bridge has LED lights on it, but unsure about the actual freeway lighting.

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RIDOT plans to have all their lights be LEDs within the next year.

UPDATE: I-95 is LED up to Exit 15 now. Exit 15 through Exit 30 is still HPS.

All RIDOT-owned lights on I-295 are LED (Exits 1, 2, 4, 5, 6, 7, 8, 9, and the State Police Barracks)

Rte 6 is LED from the I-295 terminus to the Rte 6/10 merger.

The TF Green Airport Connector is LED now.

Rte 37 is entirely LED.

Rte 146 is all HPS except for the I-295 interchange (exit 9 in I-295; exits on 146 are not numbered) which is in the process of being LED'ed at this time.

So RIDOT has made plenty of progress in the past two months! The remaining HPS lights are all along continuously-lit stretches of road, so while most of the state's freeways are now LED, there are probably still more individual HPS lights left than individual LEDs. Just more LEDs area-wise.