My understanding is that conforming allows lenders to write loans to a universal set of standards ("conforming" to those standards), with the understanding that the loan will then be eligible for purchase by one of the GSE's.
The standards have become much tighter recently, especially in regards to the relationship of Credit Score to LTV (ie you wont be able to qualify for 90% to 95% LTV if you have a credit score in the low 600's); and Debt to Income.
Because these loans conform to the standard for GSE purchase, there is less risk to the lender that the loan will be unsaleable on the secondary market, which would force the lender to hold onto it.
Due to the minimized risk, lenders will underwrite these loans at a lower rate than non conforming loans that they might have to sit on.
In terms of the impact on the local market, a raise in the conforming limit will not help the key issues:
High debt to Income caused by high prices
High LTV caused by high prices
Current homeowners that are upside down.
This will help buyers who can already qualify for the home that they like by lowering the interst rate.
If there is any piece of news that foreshadows the near term future for OC, it was the report on CR that a high percentage of loans that had been modified already were still going into default.