Google changed its algorithm by adding one more factor -- file name, folder name

The problem isn't that Unix doesn't LIKE capital letters -- it's that it treats them as unique.

For the domain name, regardless of the server type, www.mydomain.com is the same as www.MyDomain.com ...

Howver, if your site is hosted on a Unix server, www.mydomain.com/MyPage.html and www.mydomain.com/mypage.html are seen as separate pages, while on a Windows server, they are seen as the same page.

For uniformity, it's therefore best to use lowercase page names.

 

I remember this being long time ago, maybe I missed the filename part.

 

Yeah, I kind of left out one part of the idea.
You should use the filenames as breadcrumbs (/camping/tents.html, /camping/sleeping-bags.html, /camping/bag-tent-combos.html) regardless of the domain. Without hyphens or the additional filename or folder, sleepingbagsandtents is useless. Sand bag? Ping ten?
Perhaps 'and' hurts more than it helps.
I'd think that Google would give extra credit to sleepingbagsandtents com/sleeping-bags.html for allinurl:sleeping bags because it can then see the domain is meaningful - it sees sleeping bags right off the bat. It may not highlight it, but it seems to add something. (The slumberjack result showing in the top 10 for Google is interesting for other reasons...)
Just as there are many types of bags, there are other kinds of tents. Surgical, party, circus. By throwing in a directory, camping, and filling it with content about tents and sleeping bags, the whole url becomes meaningful for sleeping bags, tents, and camping.
You could also then easily add keywords like camping stoves, cookware, etc.

 

I noticed this issue about 2-3 months ago and posted at seochat. Don't remember who was, but someone said it's just highlighting purposes. I found it so logical.
As Compar mentioned, it doesn't highlighting capital letters this is another evidence for me that again this mostlikely just highlight filter.
At the end of the day I use keywords in my page file names. As I'm %100 sure at least MSN uses as a ranking factor.

 

Havent read all messages, but as far as I know, this is a high factor, of getting your website over optimalized. Be careful when changing all directory names into keywords. You might hit Google filters. It happend to me