You could have always configured two SSD drives in a RAID 0 format. However, the issue is that the controller/software could not implement the TRIM feature on the newer (now more standard) drives. TRIM was where the data deleted from the SSD would be wiped as it was deleted. This would cause drives that were getting close to being full to slow down. Now-a-days, you can configure them in a RAID if the RAID Controller supports TRIM of the SSD in the RAID setup.
Here is an article of Intel incorporating TRIM in the their RST Software.
Here's more of an updated article. It looks like the Intel RST Software required for TRIM support on RAID configurations are available, but will not be officially released until later this year.
However, since TRIM is an OS Supported/Driver Driven technology, you may be able to find a third party SATA RAID Controller that has TRIM Support built in.