I was working on building out the BizTalk 2013 environments for a client when one of the guys in IT mentioned that the BizTalk PowerShell snap-in was not updated for working with BizTalk 2013. The CodePlex site at http://psbiztalk.codeplex.com/ mentions the currently released version only works on BizTalk 2010.
So I downloaded the source and rebuilt from my BizTalk 2013 VM. I only had to go through the migration wizard and install WiX to get all of the projects to build. Then I ran the installer and started using it from a PowerShell prompt. It appears to be working fine to me. I uploaded the file as PSBizTalk BizTalk 2013 Verison 0.1 to my SkyDrive. (update: I updated the provider officially on CodePlex. Please go to the 188.8.131.52 release page).
I did not increment the version information or do anything else you might expect would be done, just rebuilt it into the MSI so you can use it in your BizTalk applications. Please let me know if you try out the updated version and if there are any issues.