Well, my preliminary, not-very-scientific, eye-witness results are back and the story is good, so far. While I am seeing lots of fragmentation on the new SSD drive that I now use for FSX, loading times have improved anywhere from 30 to 40 percent at least (and that's with some added gigabytes of terrain installed).
The more important non-scientific observation, though, is the significant reduction of "the stutters" which I attribute to the much lower read access times on the SSD (~ 0.2 ms) compared to the traditional hard drives which are anywhere from 5 to 12 ms (for some older disks).
I'll report more results as I see them. One other consideration to be made here, though, is that this generation of SDDs is still "the slow one" - there's a new one coming out (at higher price tags, though, so it might be directed to enthusiast-simmer levels and above, for the moment), with double the existing read and write abilities. The future's interesting, to say the least!
PS. I am waiting on Diskeeper corporation - they have promised me a license of their new Hyperfast product which integrates with the main Diskeeper 2009 application and allows SSDs extended lifespan and faster performance. Testing of Hyperfast will commence shortly!