To be more precise, this German design firm were retained as Apple's industrial design consultants for a period starting shortly after the creation of the first Macintosh, and ending shortly after Steve Jobs' departure from Apple. They did not design the original Macintosh. This was designed by Jeff Manock, the same man who designed the Apple II. Other elements associated with the Macintosh 'look' were also designed in-house, such as the Macintosh GUI.
What frogdesign did do was create a consistent design language for Apple's industrial design. This was applied to all of Apple's products, including later versions of the Macintosh. It featured a distinctive pale beige colour, and grooves running along the sides of the product, from front to back (never from side to side). frogdesign's contract with Apple effectively made frog head honcho Harmut Esslinger Apple's head of industrial design.
Apple always retained an in-house group, however, and more recent Apple design coups, like the iMac and the G4 Cube were also done in-house, by Apple's Industrial Design Group, headed up by Jonathan Ive. frogdesign are so strongly associated with Apple's design work, however, that the original Macintosh is credited in many catalogues and design books to Esslinger.
The web site of frog (as they apparently prefer to be known) is messy, but interesting, and advertises a prodigious number of jobs. If we put our heads together, we could all end up working for them. Here's what they say about their work with Apple:
As Steve Jobs searched for a
world-class design firm, he realized
his goals matched ours: to marry
design with technology for the benefit
of all - and to make design
competitive insulation for Apple.
Together, we created the unified
design language known as Snow
White, instantly recognizable for its
friendly, white, high-tech shapes and
clean graphics. First at bat was Apple
IIc, which sold 50,000 units the first
day and became Time magazine's
Design of the Year. The Macintosh
series followed, achieving even
greater success. Apple is the
landmark case for the value of
design: it entirely leveled the
psychological, emotional barrier
between people and PCs.