I got that too and noticed the typo in their sample PHP code for the Host: header.
Even after correcting the typo for the new HTTP 1.1 request, I'm finding my postback verification is being hung up for a long time before I get a VERIFIED response, during which time Paypal sends me duplicate IPN notifications. I'm switching back to HTTP/1.0 requests for now since it worked just fine before and I don't have time to debug this right now.... thanks Paypal...
Not to mention other platforms are more popular in other countries. For example, Google's Orkut is very popular in Brazil and I'm sure Baidu et al are working on offerings for the Chinese market. USA != world
Even after correcting the typo for the new HTTP 1.1 request, I'm finding my postback verification is being hung up for a long time before I get a VERIFIED response, during which time Paypal sends me duplicate IPN notifications. I'm switching back to HTTP/1.0 requests for now since it worked just fine before and I don't have time to debug this right now.... thanks Paypal...