Open source licenses, using licensed source code under new licenses

[Ryan S. Pettigrew]

	I have unwittingly run into a case where I’d like to release code  
under Open Source license x, but it uses code under Open Source  
licenses a, b, and c. First, are there any licenses that a, b, c, or  
x could be which can be used together, unchanged, in this way?  
Second, do I need a lawyer to determine whether the licenses can be  
used together, or is it something I can determine on my own? Third,  
will I need a custom license for x, or can it be a standard license,  
in spite of having to preserve the terms of a, b, and c? I realize  
that, in general, this may fall outside the purview of your site or  
discussion; however, a license that can incorporate code from more  
Open Source licenses would be very useful.

																		Ryan Pettigrew