This program is presumably directed at countries where credit card use is already common. If you happen to use a credit card anyway (and this deal is available where you live), then switching to this is an essentially no-cost way of donating to SIAI (unless you have a rewards program on your card that's very good). If you don't live somewhere where credit cards are acceptable/viable, or if you don't have one personally, it probably isn't a good option for you.
Many cultures have a stigma against credit cards and/or debt in general.
Luke posted about this on SIAI blog. Essentially, you can get a credit card with cash-back rewards program that automatically donates money to Singularity Institute.
This seems to me like a dream come true. Am I missing something? Are there any catches? Is there a better rewards program, which I can use to save more money, so I can donate more money to SIAI?