Has anyone asked if there will be an Art Gallery for 5e, particularly the Monster Manual art? If so, any ETA on it? I don't use twitter, so I can't do it myself. And we know they don't read the forums. 
I did a search, and surprisingly it doesn't look like anyone else has asked about that (since 4e). But my Google-fu could have failed me yet again...
they don't really release those anymore. you might have some luck checking if the artists have put the pieces up on their blogs or something.
There are some art galleries on the website, including one for the MM. They're kinda hard to find, though. Here's a link: http://dnd.wizards.com/articles/media-resources/art-galleries
Just going to comunity you can find a large ammount of art. http://www.pinterest.com/dndwizards/
They uploaded a lot of it on Pinterest.
Thank you for the info and suggestions!
I will definitely second the art archive they have up at Pinterest. 
Quite a bit of pillage-able artwork there and I know there will definitely be more. 
Lots of times MM art (old and new) comes up if you google image search for the specific creature's name.
But, yeah...WotC should make the art more available. I hated how you had to have a DDI account to even view galleries online. That was a BS move.
TSR published at least two art books, also. The Art of Dragonlance, and the Art of Dungeons & Dragons.
WotC really should follow suit. Those two art books got me interested in D&D back in the 80's. Anything that brings people into the world of D&D is a good thing. Also, fantasy is popular now, largely due to Harry Potter and the LotR films. Non-TTRPG players tend to think of D&D as dry and all about math and charts. Seeing the excellent illusrations they use would go a long way to letting a wider audience know that it's not just a game for statiticians. D&D badly needs new blood.