Speaking as someone who has years of experience dealing with "the sex offender issue," I can tell you that this law (like many others proposed at the state level) will be counterproductive. Some states and the Federal Government currently have the ability to keep dangerous individuals locked up indefinitely. It's called civil commitment.
Recently, in Missouri, several state senators have begun speaking up about more intelligent legislation regarding sex offenders. The unintended consequence of having harsher laws is that they further remove an individual from society. It is that removal and isolation that prompts them to delve deeper into deviancy.
We need laws that allow for tracking, but that do not create further punishment where no more criminal acts are involved. Also, about 4-5% of "sex offenders" are the really heinous ones we hear about on the news. The other 95% are unlikely to commit another sex crime.
For more accurate information, see the article "Misunderstood Crimes
" by Hal Arkowitz and Scott O. Lilienfeld, featured in Scientific American Mind, April/May 2008, page 78-9.