According to AMD's website, pricing for high-end Athlons, including the FX series, X2 5600+ and 5400+ remains unchanged, while the X2 5200+ saw a hefty cut from US$403 to US$295. Reductions continue down the rest of the range with prices falling around US$25 at the top of the scale to around US$15 at the bottom.
The price of the single-core Athlon 64 3800+ also fell from US$108 to US$101, however, the price of the slower 3500+ remained unchanged. Prices for the lowest speed CPU, the Athlon 3200+ is no longer posted on AMD's website.
Here's a table with most of the price cuts:
AMD Athlon 64 pricing, Dec 5, 2006 and Jan 22, 2007 (US$)