Virtual Memory and SSD
I am using a 60GB SSD as a dedicated virtual memory drive running on windows 7 it is SATA-3 and I'm getting speeds of 450MB sec.
My machine is fully loaded with 32GB memory in all available slots. I'm using this machine to edit feature length movies in HD so this memory is quickly eaten up.
I have to say that the SSD virtual memory drive is a great help in reducing the bottleneck when memory runs low and VM kicks in. I don't care if the drive dies in a year or two, I'll just replace it with another cheap drive.
While people are suggesting you do not put a page file on SSD there is nothing to stop you, there are also similar-ish ideas such as Microsoft's Readyboost, though it uses a USB stick instead of an SSD. It works in a vaguely similar fashion (caching hard disk reads instead of caching virtual memory - but the theory of the method of performance boost and flaws are the same) but has very similar reasons for limitations as putting a page file on an SSD:
Flash based memory has much poorer write tolerance than spinning-platter or full-on memory chips. Typical flash devices these days are getting as low as 5,000 write cycles for a standard MLC device, with the manufacturers using wear-levelling algorithms to help the device last longer. Sadly it seems that many SSDs fail after 1-2 years (see here for some failure rates during the first year), but this is typically due to failure of the SSD's hardware or firmware, rather than wear of the flash memory.
USB sticks are dirt cheap, come in all the major helpful sizes (4GB, 8GB, 16GB and so on) and for small reads and writes are pretty comparable to an SSD. They suck at bulk transfers though.
There is also Intel's latest Smart Response which is effectively another version of the ReadyBoost technology.
So as long as you don't mind the idea that you could potentially wear the SSD out faster (though no faster than putting the entire OS on the SSD to be honest) then there is no reason not to put your page file on the SSD as it should perform better than the hard disk.
SSDs are slower than RAM, but faster than HDDs. So, the obvious place for an SSD to fit into virtual memory is as swap space (swap partion in Linux; page file in Windows). The operating system automatically uses the swap space as needed when RAM is in short supply, so by putting swap on the SSD, you get faster-than-HDD performance when swap is needed.
On Windows the page file normally lives at C:\pagefile.sys, so to put that on SSD you'd have to either put your C: drive on SSD, or somehow tell Windows to put the page file elsewhere.
The other method that you seem to be suggesting is to somehow make the SSD look like additional RAM to the OS. I don't know how you would do that, but I agree that it would be a bad idea, since SSDs (flash memory) are slower than RAM.