It's not correct to say that Picasa is emulated using wine. Instead, it's a native Linux app that has been ported using WineLib, which reimplements a lot of the Windows API, but compiled to Linux. Instead of replacing API calls with the Linux equivalents, there's just an additional layer that redirect calls or implements them.
Picasa for example is emulated through wine on Linux/Mac, but that's because it was developed originally for Win32.