VelocityReviews.com has posted a review on the Corsair XMS 2048-3500LL Pro 2GB Kit:

Some people think these modules are just another set of XMS Pro's but that's not it, they're something more. 1T command rates, 2GB, 2-3-2-6... Is your mouth drooling yet? You might want to clean the puddle up before you fall over. If you looking at 2GB Kits Right now and you haven't even considered these Modules, you're missing out on them! These modules are the modules you want for gaming, they have the "Bling Bling" and they have the Performance, I have been playing many games whilst having these modules installed and they are way faster at loading then any others I have seen, in fact so fast that I have already started a Counter-Strike Source Match before anyone else has joined.

Pros (+):
- XMS Heat spreader
- LED Activity lights
- Can do 267MHz at 3-3-3-8
- Run SPD Standard at 2-3-2-6
- Rated at PC 3500!
- Speedy, on all software and games
- No requirement for a high priced Mother Board to run it at Stock Speeds (PC3500)

Cons (-):
- Ram is a slight be tall, some people might have to think if they will fit in with their HSF
- Ram really doesn't like the extra MHz's when it gets to the high 260's and the low 270's, but this ram was not made for Overclocking

In related news, DriverHeaven just posted a review of Corsair TwinX 2048-4000PT kit:

To begin with, we especially enjoyed the overclocking capabilities and performance of the modules which are both well above average. The facts that the modules ran up to 278MHz without any burn-in, only 2.9V worth of voltage and at 1T command are enough for solidifying the previous claims. The price of the modules is another positive point, as the modules may not be the cheapest kit available but certainly are reasonably priced for 2GB worth of serious RAM.

What we did not like: The only negative point that we could imagine concerning these modules is that they are unable to run at very tight timings (such as 2/2/2/5) and that they do not react well at high voltages. They are not meant for extreme overclocking or for score benchmarking.