Sounds like a bit of a silly question, but exactly how long, or short is a short story? I've think I've read one or two that were approximately five or eight pages on 8 1/2 by 11 paper.

However long you like. A good deal of the short stories people commonly read, espeically online, are between 2,000 and 4,000 words. However, most short stories that are published in print are usually in an anthrology or a collection or combination of short stories of sorts, and they're usually 7,000 - 14,000... after that I think they're technically considered a novella, but I'm not sure.

Well, short stories less than 1000 words are technically flash fiction, so you should aim for longer than that.

From Wikipedia.com:

Determining what exactly separates a short story from longer fictional formats is problematic. A classic definition of a short story is that it must be able to be read in one sitting (a point most notably made in Edgar Allan Poe's essay "The Philosophy of Composition" of 1846). Other definitions place the maximum word length at 7,500 words. In contemporary usage, the term short story most often refers to a work of fiction no longer than 20,000 words and no shorter than 1,000.

Stories shorter than 1,000 words fall into the flash fiction genre. Fiction surpassing the maximum word length parameters of the short story falls into the areas of novelettes, novellas, or novels.

I found these length descriptions on another writing forum which seems to be pretty fair:

Standard lengths for fiction are:

Short short--under 2,000 words.
Short Story--2,000 to 7,500 words.
Novelette--7,500 to 17,500 words.
Novella--17,500 to 40,000 words.
Novel-- anything over 40,000 words.

But if you want to sell a first novel, odds are very high it will have to be between 80,000 and 120,000 words. Under 80K is tough to sell, and over 120K is tough to sell, if you're a new writer. But a 100K novel will fit the majority of book lines out there perfectly.

I dont really think theres a guideline for short stories. Basically, it can't be a whole book. I believe that would be the ground rule.

like kind of a section?

However long you like them to be. I once read a short story that was 25 pages long on 8 by 11 paper.

If it's 100 pages or more, it's a novel. If it's anything shy of that, it's a short story.

I use A4 paper and print using Microsoft Word as standard, so i work by word count. I'd say about 2000 - 5000 words.

Anything that can be read in one hit is a short story, apparently. Short stories are normally under ten A4 pages

you should only consider word count, not pages... that's all editors go by... and to the professional writing/publishing world, 'anything that can be read in one hit' is not a 'short story'... see the categories listed above by hylo, for the industry standards... add to that, under 1,000 is 'flash fiction'...