For the system partition, no, it's probably not worthwhile at all. The main advantage you get from SSDs is their ability to do random reads at practically the same speed as sequential reads. An SSD is electronic, not mechanical, so you aren't required to wait for the disk to spin and the head to move for data to be read.
If you were going to run SSDs on the database array, which DOES perform a lot of random reads and writes, you could notice significant improvements over conventional disk arrays. Again, databases such as SQL Server or Exchange Server perform a lot of random read operations which SSDs are highly efficient at performing.
However, for the system partition, you're not going to see an awful lot of data read and written back to that once the system is booted. Sure, it will have a lot of activity during boot-up, but after that, system partitions are generally subjected to much less activity than your Database or Logs would be subjected to. As such, you're not going to notice much benefit in throwing SSDs onto it. Just about the only I/O of significance might be the page file, but I wouldn't worry too much about that; the performance improvement vs. the cost of an SSD RAID 1 over a conventional Hard Disk RAID 1 on a decent controller would, in my opinion, be difficult to argue on the performance aspect.
If you have spare funds lying around which you are looking to spend, I would spend them elsewhere. Perhaps purchase 15 000 rpm disks rather than 10 000 rpm disks, use a server which uses SAS over SCSI, add some more RAM, a second CPU and so on.
-Matt
