I have in the past called the dos commands from the Remote Server
Administration Tools (RSAT) feature pack (Win7
http://www.microsoft.com/en-us/download/details.aspx?id=7887) from Cygwin's
shell.  I've spent a fair amount of time cleaning up their cruddy output and
making useful wrappers (although not complete) to these DOS tools for
cygwin/bash.

Now in Cygwin 1.7.29 and 1.7.30 they do not return any information from these
tools.  A call to dsquery.exe without args should show usage, now it returns
nothing.  
Launching "cmd.exe" in a cygwin shell would allow calling those tools
interactively (but not really usable) but return nothing now.

Once installed these tools are available from C:\Windows\System32\ in the
Windows System PATH and available to Cygwin inheriting that path.  I am not
pathing to the tools in these examples but directly calling it using absolute
paths does not solve the problem.

$ dsquery.exe user -name "test user" 
"CN=Test User,OU=Users,OU=Test,DC=domain,DC=com"

which you could pipe to dsget as in:
$ dsquery.exe user -name "test user" | dsget user -email
 email
 test.user@domain.com
dsget succeeded

None of this works anymore in the latest Cygwins, I am not sure when it broke.
 I wrote some pretty fancy wrappers to cleanup the output and simplify calling
from cygwin which is not getting any output.  

Calling command.com directly in cygwin used to work, now just returns the
command name:
==================================================================
$ cmd
Microsoft Windows [Version 6.1.7600]
Copyright (c) 2009 Microsoft Corporation.  All rights reserved.

C:\>dsquery
dsquery

==================================================================

older cygwin worked:
==================================================================
$ cmd
Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation.  All rights reserved.

C:\>dsquery /?
dsquery /?
Description: This tool's commands suite allow you to query the directory
according to specified criteria. Each of the following dsquery commands finds
... <snip>
==================================================================

older cygwin worked fully:
==================================================================
C:\>dsquery user -name "test user" | dsget user -email
dsquery user -name "test user" | dsget user -email
  email                    
  test.user@domain.com  
dsget succeeded
==================================================================
a plain call w/o args will display a usage which works in older cygwins.  This
was around March/April.  1.7.29 is dated 2014-04-07 but I'm fairly sure it was
working then.  Not sure what environment settings would affect this.

I can get output in cygwin from this call but cannot pass args to this
command:
==================================================================
$ dsquery user
"CN=...."
.... <snip>
"CN=...."
==================================================================
lists CNs but not all of them in lower OU's, you will need to call dsquery
w/args for that.

I don't think I can get an older cygwin (1.7.28?) installed to see if it was a
change there.  I've tried RXVT and mintty in cygwin with the same behavior. 
Most my tests from old cygwin is an instance older than the 32/64 bit split
but I know I had it working a month or so ago in cygwin 32bit.

Attached cygcheck output