I don't usually go to Wikipedia for info, but apparently they have more recent polls than any other site posted. So there have been four since the one above; five total in the last month.
The UC Berkeley poll seems to have been conducted independently (as opposed to being commissioned by another party) and took place from April 16-22 It surveyed 1,738 likely voters and has a margin of error of +/- 3.5%. The next poll was conducted for several groups by SurveyUSA (San Diego Union Tribune; KABC-TV Los Angeles; KFSN-TV Fresno; KGTV-TV San Diego; KPIX-TV San Francisco) and took place from April 19-23. It surveyed 520 likely voters and has a margin of error of +/- 5.5%. Next is a poll commissioned by John Cox's campaign and conducted by Smith Johnson Research from April 26-27. It sampled 533 voters and appears to have adjusted the numbers based on a simulation of turnout results or something like that. It has a margin of error of +/- 4.2%. Next is a poll conducted by Big Data Poll for the Travis Allen campaign from April 27-29 and sampled 1,442 voters, weighting them based on likely voter status and enthusiasm, it appears. It has a margin of error of +/- 3%. The most recent is a Gravis Marketing poll commissioned by One America News and conducted from May 4-5. Sample size is 525 likely voters. Margin of error is +/- 4.3%.
So here are the results in order of the date of the polls followed by an average (rounded to the nearest percent), with candidates listed based on the average:
Newsom.....30%.....21%.....36%.....24%.....22%.....27%
Cox............18%.....15%.....20%.....11%.....23%.....17%
Villaraigosa...9%.....18%.......8%.....14%.....19%.....14%
Allen...........16%.....10%.....13%.....12%.......8%.....12%
Chiang..........7%.......9%......4%.......9%.......9%.......8%
Eastin...........4%.......1%......4%.......5%.......4%.......4%
Other............3%.......8%......0%.......---........2%.......3%
Unsure.........13%.....17%....16%.....26%.....13%.....17%
Even with the smallest margin of error applied to the average, Allen, Cox, and Villaraigosa are all in contention for second place, with Cox appearing to have the edge. Only one poll shows Newsom in second, and there he is statistically tied to Cox. Newsom is basically guaranteed a spot and will almost certainly be in 1st place. Chiang, Eastin, and the rest don't stand a chance of getting in the top 2 as things stand right now. There are enough uncertain voters that it'd be hard to make a good guess at who will come in second. Decent chance that it will be one of the two leading Republicans, though.