If you don't have an Intel-brand SSD: READ THIS.
Watch out !! -- I was blithely mislead by 'smartmontools.' I have a Samsung SSD, and the smartmonitor/'smartctl' tool happily misreported that '233' (hex 'E9') attribute was 'Media_Wearout_Indicator'; in fact -- no, for Samsung (and other manufacturers) it is up to entirely different. This and other forum postings, stack-exchange question/answers, and power-user blogs I found seem to be 'Intel focused,' with only vague hints that 'it may vary.' (Versus any suggestion that you need to watch out for wrong and erroneous labeling of the attribute by smartmontools).
As I was preparing to copy my SSD to a new harddrive I'd bought (because of what smartmontools had told me), I booted to windows (I have a dual boot system), to learn something about SSD's from what the windows-only Samsung tool 'Samsung_Magician_v43.exe' had to tell me about my drive -- it was shockingly uninformative.
After what's been hours of digging - I've finally been able to run the windows only tools: hddgaurdian - ' code.google.com/p/hddguardian', and then also CrystalDiskInfo: Surprise! both tools independently tell me my Samsung SSD is 'just fine' (hdd guardian says '5 stars' and Crystal Disk "98% OK"). By contrast the smartctl tool explicitly labeled the attribute with 'decimal- 233 / 'hex- E9' as "Media Wearout Indicator" -- and told me its value was "1" or 1% -- an indicator of (the risk of) pending failure. To be as sure as I can, I dug and dug and was finally able to locate at least something from Samsung official: " http://www.samsung.com/global/business/semiconductor/minisite/SSD/us/download/07_Communicating_With_Your_SSD.pdf" The document indeed implies that the attribute 'hex E9' /'decimal '233' is not used by Samsung the same way. ( Samsung: I'm very disappointed, please either fix your official software-tool, or at least make it clear that you do not provide wear out indication information!)
Further - if you have neither an Intel SSD nor Samsung SSD - be warned, this info does seem to vary across manufacturers. ( e.g. see the attribute label chart on 'code.google.com/p/hddguardian/wiki/about_reliability' for the only useful indication of the degree of variability that I found. )
The so-what: If you don't have an Intel SSD-- do not be mislead by the false attribute name labels provided by smartmonitor. Perhaps it will improve in the future, but the version installed by default for Ubuntu 12.04 LTS (April, 2014) was total fail. Instead of telling you it 'doesn't know' -- smartctl just mislabeled the attribute. I did not find another tool for linux that made the 'correct' information transparent or clear.