I think, the above three posts covers most of them. But, below are some of the things which we need to consider as well.
- Unsupported characters: These characters are not allowed in SharePoint or WSS /\:*?"<>|#{}%&~ or tab characters and multiple periods.
- File or folder names with Trailing spaces: File or folder names in SharePoint or WSS won't support any trailing spaces.
- File and folder names length: File or folder names longer than 255 characters will not be allowed.
- Number of columns limitation in a list:
- 64 text fields, including the following field types: Single line of text, Choice, Hyperlink, or Picture.
- 16 Lookup fields
- 16 Date and Time fields
- 16 Yes/No fields
- 32 Number and Currency fields
- 32 Multiple lines of text fields
I believe these are enough for a SharePoint architect to get good idea on limitations of SharePoint. Hope these helps and please update me if you find any.