You can use the New-RestoreDatabaseFromMark
cmdlet with or without specifying the mark. Leaving the mark empty is equivalent to last mark.
Microsoft Script Center focuses on teaching people how to use Windows PowerShell and VBScript to reduce time spent performing mundane tasks. Through script center you can find many PowerShell scripts and a few on BizTalk:
Great resouces "guide" Steef-Jan!
Great resource list Steef, I added new resources