The Transformers Live Action Blog has posted pictures from the set at Holloman Airforce Base.  The aren't overly revealing, but pretty cool nonetheless.  They have also posted some interesting fan made art, imagining what Grimlock might look like, should he wonder onto the set (with a truck alternate mode).  Here's hoping!

Also, just a quick note, seibertron.com appears to be down because of flooding at both his Chicago home and central servers in Houston, Texas.  Luckily only a couple of his transformers were damaged... So if you cannot log in, don't worry, no-one can.