List Item level Security in sharepoint

Set Item Security based on Content Type that it is created from, and the based on the security groups (naming convention is used to tie them up)
http://mindsharpblogs.com/pauls/archive/2007/05/07/1754.aspx

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http://www.endusersharepoint.com/2008/12/23/security-trimming-a-list-view/

Here’s a question that comes up quite a bit. This time, it was on Stump the Panel:

Does anyone know how I can use one SharePoint List but have different site users only access specific views (kinda like security trimming views) The scenario is I am working with some lawyers who should only access data on the list they are responsible for and shouldn’t see the data the other lawyers are responsible for. I want to only maintain one list so that its easy for me to update just the one list.

Response from Paul Grenier, Moderator of Stump the Panel:

Perfect reason to use folders. Folders can have their own permissions. You can break inheritance and give every object in them the same permissions. This allows you to group things in a list or library by permission. Works great for things like a library of personal expense reports.

"you can set views to not show folders"
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http://www.siolon.com/blog/the-folder-less-sharepoint-paradigm/
Post opposing folders and using views instead. But provides no idea on how to implement item level security.
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http://www.infoq.com/articles/Dressel-Gogolowicz-wss-security
Column Level Security in SharePoint, by defining a custom field type(inheriting from SPFieldLookup) and using that as a lookup column from another list.
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