When I was a wee lad, the portable gaming market consisted of a green and black screen GameBoy and the battery sucking SEGA Game Gear. My how things have changed.
Today, we have the Nintendo DS and the Sony PSP, and, according to DFC Intelligence, a research firm, the portable gaming market could exceed $10 billion this year.

$10 billion this year!?! Holy wow. That's not the entire gaming industry, just the handhelds.
DFC also states that the Nintendo DS may well go on to become the best selling piece of gaming hardware ever, beating the current record of 115 million PS2s, and, that the combined sales of the DS and PSP, by 2011, could outsell all gaming consoles combined.