This map appears to be from the Australian Radiation Services. It is, in fact, a fake that doesn’t accurately reflect fallout patterns at all. It is designed to terrorize people, so if you see it, let whomever sent it to you or posted it know that it is not from the ARS. This is their disclaimer: "Australian Radiation Services is aware of information about radioactive contamination being spread from the Japanese nuclear reactor incident released under the ARS logo and name. We wish to be clear that this information has not originated from ARS and as such distance ourselves from any such misinformation." In fact, even if all four reactors melted down completely and burst their containments, the US would need to monitor radiation levels carefully and take action as necessary, but it would not be catastrophic here. For the Japanese, it would mean a much more serious situation, obviously, and a long, difficult and dangerous cleanup period.
The bogus text message, allegedly from the BBC, is being spread primarily in Asia. This is the fake message in full:
"BBC Flash news : Japan Government confirms radiation leak at Fukushima nuclear plants. Asian countries should take necessary precautions. If rain comes, remain indoors first 24 hours. Close doors and windows. Swab neck skin with betadine where thyroid area is, radiation hits thyroid first. Take extra precautions. Radiation may hit Philippine at around 4 pm today. If it rains today or in the next few days in Hong Kong. Do not go under the rain. If you get caught out, use an umbrella or raincoat, even if it is only a drizzle. Radioactive particles, which may cause burns, alopecia or even cancer, may be in the rain."
In fact, swabbing the skin with Betadine is useless, and the likelihood of any Iodine 131 radiation reaching as far as other countries is not great. In any case, as Iodine 131 has a half life of only 8 days, it quickly loses its radioactive impact. The CDC recommends that nobody over the age of 40 take supplementary iodine unless they suffer direct radiation exposure, as older people are more vulnerable to allergic reactions from the iodine than they are from radioactivity-induced thyroid cancer.