Digital Trendsによると、Appleが新たに開発した12インチRetinaディスプレイのMacBookのロジックボードサイズはシングルボードコンピュータRaspberry Pi B+よりも小さいそうです。

We’ve been diving deep into the new MacBook today, seeking every last morsel of information. In this search we discovered an interesting factoid; the logic board of the MacBook is actually smaller than the famous Raspberry Pi.
[The MacBook's logic board is smaller than the Raspberry Pi - Digital Trends]

　Raspberry Pi B+のサイズはIOポートの突起を除いて85.6x56.5 mm、そして新しいMacBookのロジックボードは116.84x38.1 mmなので前者の面積は4836.4 mm^2、後者は4451.6 mm^2となりかなり小型がされているのが分かります。

By our calculations, the logic board is 4.6 inches wide and 1.5 inches deep, rounding to the nearest tenth, and not counting a tiny sliver of circuit board that protrudes on one side. [...]Meanwhile, the Raspberry Pi measures about 3.4 inches by 2.2 inches (rounding to the nearest tenth). That works out to 7.48 square inches, a full quarter of a square inch larger than the MacBook’s logic board.
[The MacBook's logic board is smaller than the Raspberry Pi - Digital Trends]

　さらにその薄さはRaspberry Pi B+の10分の8以下で（MacBookの最厚部 13.1 mmの中にすべて収まる）、「マーケティングの視点や目的が違うため比較できないがAppleがこれほど小さいスペースに合うようにロジックボードを設計しているのが印象的だ」としめています。

Obviously, the logic board of the MacBook and the Raspberry Pi are not comparable from a marketing standpoint, and are meant to fill different roles, but it’s impressive that Apple has managed to fit so much in so little space.
[The MacBook's logic board is smaller than the Raspberry Pi - Digital Trends]

Raspberry Pi Model B+ (Plus) [エレクトロニクス]

raspberrypi.org