ASC 820 (Formerly SFAS 157) Amended January 2010:

ASC 820 (formerly SFAS 157) has been significantly amended since its inception. ASU 2010-06 Improving Disclosures About Fair Value Measurements is a significant amendment effective for financial statements beginning after December 15, 2009 (except for disclosures about purchases, sales, issuances, and settlements in the roll forward of activity in Level 3 fair value measurements which are effective for fiscal years beginning after December 15, 2010). 

The essence of ASC 820 remains unchanged but there are some significant changes to disclosure requirements. Per ASU 2010-06.

ASC 820 Before ASU 2010-06		ASC 820 After ASU 2010-06
Transfers into and out of Level 3 (changes in valuation technique); discussion of changes in valuation techniques		Transfers into and out of Levels 1, 2, and 3 (changes in valuation technique); also requires disclosure of the reasons for the change
For Level 3 inputs, roll forward disclosure of purchases, sales, and settlements (net)		For Level 3 inputs, roll forward disclosure presenting separately information about purchases, sales, and settlements (on a gross basis rather than net)
Level Input disclosure to be presented for each major category of assets and liabilities		Level input disclosure for each class of assets and liabilities
The inputs and valuation techniques used to measure fair value and a discussion of changes in valuation techniques and related inputs, if any, during the period.		For fair value measurements using significant other observable inputs (Level 2) and significant unobservable inputs (Level 3), a description of the valuation technique (or multiple valuation techniques) used, such as the market approach, income approach, or the cost approach, and the inputs used determining the fair values of each class of assets or liabilities. If there has been a change in the valuation technique (for example, changing from a market approach to an income approach or the use of an additional valuation technique), the reporting entity shall disclose that change and the reason for making it.

The above is just a summary of some of the significant differences between ASC 820 disclosure requirements before and after ASU 2010-06. I recommend a good reading of ASU 2010-06 and the current ASC 820   if your financial statements or client's financial statements will be subject to the above fair value disclosures.