As we know, "The Artist" was recognized as the best film of 2012 in the Oscar Awards.
Is this the first try to create silent film in last 20 years or have there been silent films made without such success?
Your question isn't restricted to feature films - so it includes short films.
The Giornate del Cinema Muto (Silent Movie Festival Pordenone) had a section FILM MUTI DEL XXI SECOLO/21ST CENTURY SILENTS with modern silent movies. You can search for films of this sections in the GCM-database.
Most of the films I remember were short films, made by students. Some film schools use silent films as part of the education.
Norman Studios kicked off a Silent Film Competition
Some feature films:
Silent Movie (1976) is another 'big' silent film, but already older then 30 years.
Der die Tollkirsche ausgräbt (2006, 40 minutes) is another nearly-silent movie. It is in the style of an old silent movie [black and white...) and only one actors talks.
Louis (2010) is a silent film about Louis Armstrong as a young boy and how he acquired his first cornet.
Blancanieves is a 2012 Spanish black-and-white silent fantasy drama film written and directed by Pablo Berger. Based on the fairy tale "Snow White" by the Brothers Grimm, the story is set in a romantic vision of 1920s Andalusia. (IMDB)
Here's a list of silent movies in the last 20 years:
La antena(2007) - A city without a voice.. - 7.4 IMDB rating
The Call of Cthulhu (2005) - The Call of Cthulhu is HP Lovecraft's most famous story.. - 7.3 IMDB rating
Single Bound (2010) - With the desire to leap tall buildings in a single bound, one boy tests the strength of faith and power... - 7.3 IMDB rating
The Fall (2006) - In a hospital on the outskirts of 1920s Los Angeles, an injured stuntman begins to tell a fellow patient... - 7.9 IMDB rating
All this movies have been categorized by IMDB as silent movies, or maybe part of the movie.
Although there's some dialog, Pixar's Wall-E (2008, IMDb 8.5) is virtually a silent film and would work well with the dialog replaced with intertitles.
This movie, just like all silent movies, consisted of body language, music, and other sounds for providing the setting of the movie, and even the personalities of the two characters. Yet, without dialogue throughout most of the movie, Andrew Stanton, writer and director of Wall-E, does a great job of setting the mood, as well as the entire setting of the movie. He is able to give us this futuristic world that has no hope of survival; and through Wall-E’s existence, Stanton is able to convey a sense of loneliness, especially at the beginning of the movie, but also his lovable personality to the audience.
A writer for the National Public Radio, Bob Mondello, best compares Wall-E to original silent films by saying, “Wall-E is a crazily inventive, deliriously engaging and almost wordless silent comedy of the sort that Charlie Chaplin and Buster Keaton used to make.” In other words, this movie is as close as anyone has gotten to producing a silent film as good as the ones Charlie Chaplin and Buster Keaton used to perform in, which is a reasonably good feat considering they were two of the most influential actors during the time of silent films.