How much notice must a landlord give that they will not renew a lease?

Question Details:

I year lease ending. We've had realtors coming to the door mentioning property for sale. When we checked with the property management company, they were not aware and could not find any record on MLS. Our own investigation stated - Prop on MLS until May 2011. Then came the vacate notice which will be the end of the year lease (40 days notice). Is PA law 90 days notice or is that only for evictions? Basically, what is appropriate number of days for a notice to vacate regarding a 1 year lease? Important Notice