This phrase is more common than you may think and the changes that went into effect today (September 21st, 2011) have people ranting. Even as I sit at work this morning the radio station I listen to has open phones for people to call in to complain about FB.
Looking at trends, there is definitely an increase in search volume and this increase has been on a steady rise since 2006.
The average monthly search volume for the phrase "I hate facebook" is 60,000/mo and the average monthly search volume for the phrase "facebook alternative" is 33,000/mo.
This is not a sudden increase as can be seen in the search trends below (source: Google Insights For Search)