Google has confirmed through Twitter that they rolled a Panda data refresh today impacting about 1.3% English search queries. This Panda update 23 since Google introduced Panda algorithm in February 24,  2012.
The new one impacted more search queries than Panda 22 that impacted about 0.8% of English queries. There was no signs of a major update as Google said there was no such updates coming in holidays. Though there was very strong signs of a update reported by Search Engine Roundtable but it was not confirmed by Google itself.
Its a real panic for webmasters who got hit just before holiday but a blessing for guys who got advantages.
Here is a list of past Panda Updates
- Panda Update 1, Feb. 24, 2011 (11.8% of queries; announced; English in US only)
- Panda Update 2, April 11, 2011 (2% of queries; announced; rolled out in English internationally)
- Panda Update 3, May 10, 2011 (no change given; confirmed, not announced)
- Panda Update 4, June 16, 2011 (no change given; confirmed, not announced)
- Panda Update 5, July 23, 2011 (no change given; confirmed, not announced)
- Panda Update 6, Aug. 12, 2011 (6-9% of queries in many non-English languages; announced)
- Panda Update 7, Sept. 28, 2011 (no change given; confirmed, not announced)
- Panda Update 8, Oct. 19, 2011 (about 2% of queries; belatedly confirmed)
- Panda Update 9, Nov. 18, 2011: (less than 1% of queries; announced)
- Panda Update 10, Jan. 18, 2012 (no change given; confirmed, not announced)
- Panda Update 11, Feb. 27, 2012 (no change given; announced)
- Panda Update 12, March 23, 2012 (about 1.6% of queries impacted; announced)
- Panda Update 13, April 19, 2012 (no change given; belatedly revealed)
- Panda Update 14, April 27, 2012: (no change given; confirmed; first update within days of another)
- Panda Update 15, June 9, 2012: (1% of queries; belatedly announced)
- Panda Update 16, June 25, 2012: (about 1% of queries; announced)
- Panda Update 17, July 24, 2012:(about 1% of queries; announced)
- Panda Update 18, Aug. 20, 2012: (about 1% of queries; belatedly announced)
- Panda Update 19, Sept. 18, 2012: (less than 0.7% of queries; announced)
- Panda Update 20 , Sep. 27, 2012 (2.4% English queries, impacted, belatedly announced
- Panda Update 21, Nov. 5, 2012 (1.1% of English-language queries in US; 0.4% worldwide; confirmed, not announced)
- Panda Update 22, Nov. 21, 2012 (0.8% of English queries were affected; confirmed, not announced)
- Panda Update 23, Dec. 21, 2012 (1.3% of English queries were affected; confirmed, announced)
Source – Search Engine Land