It looks like a small patch to iwinfo may be needed to properly detect and report the chipsets in the wrt3200acm.
This trivial patch (untested) against the latest iwinfo git tree should work:
diff --git a/hardware.txt b/hardware.txt
index 81b31cf..098551f 100644
--- a/hardware.txt
+++ b/hardware.txt
@@ -59,3 +59,5 @@
0x1814 0x3052 0x1814 0x0008 0 0 "RaLink" "Rt3052"
0x1814 0x3352 0x1814 0x000c 0 0 "RaLink" "Rt3352"
0x11ab 0x2a55 0x11ab 0x0000 0 0 "Marvell" "88W8864"
+0x11ab 0x2b40 0x11ab 0x0000 0 0 "Marvell" "88W8964"
+0x02df 0x9135 0x0000 0x0000 0 0 "Marvell" "88W8887"