Unless I'm missing something, I don't think there's any SSD-specific reason why you should or shouldn't give the OS its own partition. From my perspective, the whole point behind having a dedicated Windows partition is to mitigate risk and to save yourself a little time. In the event of having to reinstall your OS, your applications will be "safe" on a secondary partition.
The main argument against this is that you'll have to reinstall programs anyway because your registry will be wiped with the OS. This isn't entirely true. Someone can correct me here, but I believe some programs can rebuild their registry entries upon launching. Additionally, many installers have a repair option that'll get you back in shape without losing all your settings.
Now, that doesn't mean you won't have to reinstall anything, and it doesn't really make a strong argument for having a dedicated OS partition in my opinion. How many programs would you really have to install if the **** hit the fan? If it's that much of a concern, you're probably better off making regular backup images on a separate drive for more protection and easier recovery.