Masayuki Tachikawa, amateur astronomer from Kumamoto city, Japan, reported the detection of an optical flash on Jupiter atmosphere recorded on August 20 2010 at 18:22:12 UT.
You can find the video on the following link and below a captured screen.
Details about the observations can be found on the following web link.
After the gigantic impact observed in July 19 2009, This is the second flash associated probably to the impact of a small asteroid impact (D<10 m) this year. In June 2010, two other amateur astronomers from Australia and Philippines reported the detection of another flash, but no scare were seen on the upper atmosphere of Jupiter, even using the Hubble Space telescope.
You can’t conclude that these kind jovian meteors are getting more numerous. I am guessing that amateur astronomers are observing more often and more regularly Jupiter and they have now the capability to record short exposure video allowing them to detect these events.