When i design a logo for a client its always in vector.
as megaton has just discovered vectors which have been a staple in GD for years.
There will issues with resizing bitmap logos for different mediums.
Its always best to supply the logo in a flattened pdf file.
You can supply EPS but you have to manage fonts unless your rasterize those layers.
Most printers wont take any other file format, nowadays.
Dont forget to rasterize your font layers before export.
If you dont receive your logo in a flattened pdf then your going to have issues
trying to resolve the DPI of the logo at any size.
Most logos as well that are in a professional capacity dont have lurid backgrounds.
Usually the simplest designs are the best.
The whole animated sequence in my avatar is pure vectors from flash, I could rasterize any of the frames from it up to the size of a skyscraper wall, like what we did for a nike print add.
50 prints all the same size as the window frames on this building, then slowly one by one glued to the inside of each window eventually producing a massive picture on the side of the building as you drove by. even tho the current output is in gif i still have the vector version.
If you try that with bitmaps all your going to get is pixel hell.
My Mum just started a finance company called erpoved loans.
Now that her logo is in vector we can rasterise it for print at any size, television and multimedia/web.
so you supply the client with a bitmap version then when they choose the logo they want and pay, you supply a PDF, which is so small in filesize compared to bitmapped variants.
Another common mistake is the logos are made in rgb not cmyk.
Most designers have a pantone colour swatch they use before they get even close to designing it, choosing the best complimentary colours fromt he swatch first.
any good GD wouldnt be caught dead without one
Sample of logo design attached to this one.