Try Appcrackr IOS5 inclut gdb 1.5.1-lr11 from user_8235's Repository - MyRepoSpace.com
Been using it for ages since SinfulCrack wouldn't work for me on IOS5.1.1 - functional GUI,it's fine.
P.S. I mean add 'hxxp://bigced.myrepospace.com/' as a repo from within Cydia, not go to the web page.
P.P.S. Sometimes it has a problem (minor bash script error, line 496 or so) and fails to 'work'.
Well just use the bog basic way to 'get' the ipa: in iFile make a temp folder, throw in whatever.app, itunesartwork & the other one, itunesmetadata.plist I think. Put whatever.app into a folder called 'Payload'. Now zip up payload & the two files. Rename it to whatever.ipa.