I am thinking about spending the money on the 8GB Intel Turbo Memory for my Thinkpad. The only thing is I am not really sure what the turbo memory does. Is it for speeding up the boot or does it speed up applications? I am going to be running VMware Player or VirtualBox on this laptop so any boost I can get would be good. Will the turbo memory help with speeding up the computer when I am virtualizing something?
Intel Turbo Memory is a NAND flash memory cache device. Frequently accessed data is copied to the flash device. Theoretically, it would speed up both booting and applications, as long as there were room on the device itself. It would also serve as a cache device for writes, allowing applications (via the filesystem driver) to talk to the cache, which can handle fsync() faster than a disk device, allowing the application to continue working, while the writes are flushed from the cache to the disk in the background.
As for the visualization, you may see a performance increase in the load time of VirtualBox, or VMWare Player, but generally VM images are so large that they wouldn't fit on an 8GB cache device. If it did it's data relocation in a block based way, then you might see more benefit.
In your case, you would get 2 4GB partitions, one to serve as cache for writes, and the other for reads, so you're even more limited.
Intel Turbo Memory never really caught on, and in fact had some performance issues. Anandtech has a pretty comprehensive review that's easy to find with a google search.
I would say that for your money, you'd see a better performance gain buying one of the newer solid state disks (SSD) that are on the market now.