magnet with both poles in the same plane

It means that both poles are in the same dimensional plane. It is common - designs such as horse-shoe magnets, etc. Imagine bending a common bar magnet into a 'U' shape to bring both poles into the same plane. They are used, for instance, in applications requiring magnetic holding or lifting.

is the magnet shown in the below link represents magnet with both poles in the same plane?

http://eetimes.com/design/automotive...-Sensing-Costs

No. just a linear magnet with cylindrical shape. It's not basically different from a rod magnet.