well this not a native executable but a wine "optimized" .exe from windows. 32 or 64 you need multiarch support cuz is a 32bits .exe inside
"file skype" says "skype: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.15, BuildID[sha1]=0x3223447b98867e62fbed258aa0da4f2281ab6f11, stripped" though, and it has no other libraries etc. included.
I use wine (crossover to be specific) every day at work to run MS Office 2003. If I could, I would immediately switch to LibreOffice, but LibreOffice is still not able to handle MS Office documents properly. Most macros do not work and even the layout of normal day to day documents is messed up. LibreOffice still has a long way to go until it can be used as an MS Office replacement in daily business work.