Earlier this year CCP made a number of balance changes to frigates with EVE Online's Inferno expansion along with a number of changes to mining barges and rookie ships. This winter's expansion will bring more work on frigates along with some love for destroyers and changes to cruisers. All in all its estimated that the changes will impact nearly 20% of the ships currently in EVE. Check out the latest blog from CCP Ytterbium for a list of all the upcoming changes.
Source: EVE Ship Balance Winter Update