There is an interesting article in the Illinois Law Journal this month written by Joseph R. Fortunato regarding the City of Chicago Condominium Conversion Ordinance (amending Chapter 13-72).
Beginning January 1, 2012, the City will require developers that convert existing (usually) apartment buildings into condominium buildings to complete a "Condominium Disclosure Summary" and provide the summary to all prospective purchasers. The Summary will be in a form prommulgated by the City's Department Housing and Economic Development. I haven't seen the actual form as of yet.
The second major component of the new ordinance is tenant protection. There are several requirements the developer must meet when converting an existing apartment building with tenants including notice to the tenant of the intent to convert (this includes written AND ORAL leases dated as of Jaunary 1, 2012), and financial assistance (13-72-065) for qualified tenants.