A relatively recent paper was published 23 December 2010, which claims we have good evidence for the existence of the multiverse. The most we could conclude from this data is that we live in Max Tegmark’s level two multiverse.
I don’t want overstate the claims the authors make. They suggest that it is evidence in favor of the existence of the “possible multiverse” but it must be corroborated with the upcoming Planck data. You can read their method for how they came to their conclusions but the general key for bubble collision detection was using a specified algorithm for detecting temperature modulations that would occur in such events.
New Planck data have released since the publishing of the paper but they have specified that they are waiting on the seven-year survey so we shouldn’t expect anything too soon. You can view the Planck one-year survey image below (July, 2010).
As I’ve said before, I cannot dismiss the multiverse a priori, though I will certainly constrain my position respective to the evidence. The multiverse is not an adequate objection to the argument from fine-tuning nor is it an objection to the kalam cosmological argument (perhaps a later post for an elaboration). I want to encourage everyone to be more open to the multiverse hypothesis because there is more evidence coming in that is supporting it (don’t get me wrong, there is contrary evidence that must be weighed as well). What is beautiful about this whole situation is that cosmologists and theoretical physicists predicted the multiverse from mathematical equations (and no doubt philosophical presuppositions). If the multiverse hypothesis is true it’s a beautiful discovery because we would have gone from pencil and paper with numbers to actually finding what was predicted by those numbers. We do live in an elegant universe [per Brian Greene].
I’m looking forward to what contributions Planck may have in finding more physical evidence of the multiverse.
 Authored by Stephen M. Feeney, Matthew C. Johnson, Daniel Mortlock, and Hiranya V. Peiris.