Hi Enche, not sure if you were referring to me, but if you're a recognised journalist working for a known publication, then most companies will lend you kit to test. But believe me, there are big queues to borrow items.
That's not to say anyone can just start a website and expect to borrow stuff though. Remember I've been doing this for 17 years, including seven as a full time member of staff (culminating as the Editor) on the UK's oldest technology title, so I'm fairly well-known by most of the companies!
As for reviews of pro cameras, Bjorn is right in that there's little commerical demand for them here. I could review them, but if no-one responds to the ads, then it simply makes no money - it's like offering to work for free for two weeks.
But as an enthusiast, I am interested in seeing how they compare, so you will see some top-end cameras used in some comparisons. For instance, my Sony A900 review includes comparisons with the Canon 1Ds Mark III here:
http://www.cameralabs.com/reviews/Sony_ ... ults.shtml
And as it happens, I've been testing the D3x recently. This will be for some more comparisons...