I have storage space that is (more or less) reserved for homeschooling materials. A lot of those materials are multi-purpose, of course, and often the lines are fuzzy between what is "homeschooling" and what is just "stuff we do at home". Things that PS families would usually have anyway and just consider normal family stuff, we often count as part of 'school'... heh. Or vice versa, stuff that I don't want the kids to think of as "separate and school" but just "normal everyday stuff".
But it's like, most families need storage space for their 'stuff', craft stuff and educational books and whatever, so ours is just a little bigger to also hold curriculum stuff. ;)
Other than that, though, we don't have a homeschool 'room'. Like the above poster, we do stuff all over the house, depending on what it is. I like the idea that learning is everywhere, not just in a particular room at a particular desk.
That being said, I've put most of my daughter's "school stuff" right in her bedroom (she's 4). We've been very Montessori with her, so the most sensible approach was to have her Montessori activities easily accessible to her in her bedroom. I didn't want them separated off or just mixed in with the 'regular' toys downstairs in the playroom. The extension of that has been that as we've started doing some more formal curriculum, little by little and bit by bit, the logical place to do it for her has been in her bedroom. So she's got a little table in there where she can sit and write, and all her math manipulatives and books are on her shelves.
We do circle time in the kitchen, though, and she does computer stuff in the basement, so we're still all over the place. But the point is just that... with each of my kids, the best solution has been different. WIth my son, keeping his 'school' materials in his room was a disaster. I need to keep them in a separate place, well-organized, etc. He needs his room as his play space and 'school stuff' happens elsewhere, for the most part. My daughter is the opposite. So, do whatever makes sense for your family, there's no one right way. :)