It's cute, it really is, seeing new people to dance music listen to a song and say "Ooh! A vocoder!" when in reality they are likely hearing the wizardry of a very recent software plug-in.
You'll hear it in Madonna (in addition of vocoders, to be fair), Eiffel 65, Cher, and several other mainstream Synthpop hits. It's that "skipping effect" everybody thinks is a vocoder. In fact, in newsgroups I frequent for music hardware, they say "Okay, I've got this really cool vocoder, how do I make it sound like One More Time?".
Made by a company called Antares, it is a plug-in available in VST and TDM formats, or as a self-contained program. Its most obvious application is making a crappy singer sound like Pavarotti by making all off-pitches snap to a predefined list of notes with any percentage of precision. To make it more natural, simply tone down the Autotune. The other side of the spectrum causes the voice to immediately snap to any pitch, causing the voice to sound robotic, albeit in a different way than a vocoder.
In addition, the plug-in allows one to see the singing as an X, Y graph and manually change the pitch. Unfortunately, the GUI for this plug-in is shamefully ugly and it has a learning curve that resembles sheer cliff. The biggest downside is that it only works with monophonic sounds, like a human voice, reed instrument, or synth leads.
Shortly, the sequel to this program will be released, called Kantos. Kantos is basically a combination of a vocoder, synth, and Autotune. Not only does it let one snap pitches but also trigger samples, use a monophonic instrument to power another synth, and much more.
Antares Autotune retails for about $250.00 but will likely be discontinued once Kantos comes out.