PopCap will discount all of its iPhone and iPad games this weekend, beginning at 12:01AM PT tonight, donating all revenues from the 48-hour sale to the Red Cross in support of earthquake relief efforts in Japan. The company's iPhone games will be reduced to $1 each, while its two iPad apps, notably Plants vs. Zombies HD, will be offered for $2 apiece.

"We recently opened an office in Tokyo, and while our Japan-based employees are safe and uninjured, we understand countless others in Japan need food, shelter, and medical attention," said PopCap's Ellen Marett in an announcement for the donation drive. "Given that Plants vs. Zombies reached #1 on the iPhone and iPad sales charts in Japan, it seemed like the most appropriate game to feature in this fundraising campaign."

A complete listing of PopCap's iOS titles can be accessed via this App Store link.