Window Washer in ultrabooks

Adding a more technical bit here...
 
The space recovery functionality of Window Washer will work just fine on SSD systems.
 
The secure erase function of anything becomes a touchy subject with SSD though.  While it can be used, depending on the SSD's firmware, it may have moderate or no effect in the traditional sense, and it will definitely contribute to cell wear on the SSD.
 
The way that an SSD drive works is to spread writes across memory locations internally and remap what the drive location it tells the computer it's tracking is actually translated to in the physical memory.  On a platter-based hard drive, if the data is on sector 100, it's in a specific physical location on the drive and writing data over sector 100 will always overwrite that specific place.  By comparison, as write-spread occur on SSD, sector 100 may start on physical cell 100, but then the next time it's written, it will write to physical cell 101 if nothing else is already there. 
 
From the computer's point of view, the data that is on sector 100 is irrevocably changed, but from the physical memory cell point of view, the old data is still in cell 100 and sector 100 now maps to cell 101.  So recovering the data from a computer point of view is not possible, but recovering it by bypassing the firmware and controller and directly addressing the memory cells may be possible.
 
At the same time, the way an SSD works with any OS that supports TRIM (Windows 7 does) is more efficient and actually removes the old data slowly over time without needing to run a cleanup system.  Taking the old example, cell 100 still has the old data.  But as soon as the last cell has been written to, it goes to the first least-recently-written cell, and automatically overwrites the data in cell 100, even though it may map to, for example, sector 150.
 
SSDs really do change a lot of concepts.  Secure Erase is nigh onto impossible on consumer drives.  Defragmenting is a REALLY bad idea.  But TRIM means that normal scrambling of the "deleted" data starts happening within a few hours of normal use.
 
End result though does stand that WW will work, but doing a secure delete hurts SSDs, and Securely deleting is no longer logistically possible.  So WW becomes useful primarily for space recovery and internal privacy (Such as history deletion) from access within the OS itself and through the drive hardware normally.
 
Hopefully this extra info will be helpful.