Did it change between 3.0 and 3.5 that you can use ranks in Knowledge Local to qualify for regional feats and if so what page and book is this at?
The description of Forgotten Realms regional feats changed with the Player’s Guide to Faerûn
The Player’s Guide to Faerûn (Mar. 2004) on Feats says
Each regional feat specifies one or more character race and region combinations as prerequisites. To select such a feat, your character must meet one such set of prerequisites. For example, to select a feat whose regional prerequisite is Dwarf (Spine of the World), your character must be a dwarf whose home region is the Spine of the World.
When you choose a home region during character creation, you can select one regional feat from the list available to characters of your homeland. Even if you can choose more than one feat at 1st level (a human or strongheart halfling gets two feats at 1st level), you can never have more than one regional feat.
Regional feats are not bonus feats; you must use normal feat slots to select them. (32)
Further, on Regional Feats and Previously Published Material says
The region system in this book limits each character to one and only one regional feat that must be selected at 1st level. This rule replaces the one on page 28 of the Forgotten Realms Campaign Setting that allows a character to learn another regional feat for each 2 ranks in Knowledge (local) she has.
The regional feats presented herein are designed with the intent that a character has access to only one. Allowing a character to choose more than one may unbalance the system. (33)
The above rules are current.
The obsolete rules
The Forgotten Realms Campaign Setting (June 2001) on Regional Feats says
If you choose a home region preferred by your character class, you may select regional feats appropriate to that region. These feats represent the common sorts of talents that people from that region learn.
If you did not choose a character class preferred in your home region, you cannot begin play with one of those regional feats. You are still limited by the number of feats available to your character based on class and race.
You can acquire regional feats later in your adventuring career. With a few exceptions, any regional feats appropriate to your race or homeland that you don’t select at 1st level are still available the next time you gain the ability to select a feat.
You may even learn feats from a new region altogether, whether or not you belong to an encouraged class for that region. After 1st level, each 2 ranks in Knowledge (local) pertaining to the new region you have allow you to select feats from a single region (other than your home region, if applicable). (28)
The above rules are no longer used.