Send email or SMS with Arduino and Google App engine
Although originally designed for an aquaponics system, Instructables user "IAquaponics" has published a great tutorial describing the hardware and software required for an Arduino to send email or SMS text messages using python, the Google App python SDK and a Ubuntu OS computer. The ability to send an SMS will be determined by carrier availability in your area however the explanation of the code and the total design is very well articulated, deserving a read for at least interests' sake.
So to get started, check out the tutorial from here. And for more, we're on twitter and Google+, so follow us for news and product updates as well.
If you're looking for an Ethernet-enabled Arduino-compatible board, consider one of Ethernet-enabled boards, such as the Freetronics EtherTen - the Arduino Uno-compatible with onboard Ethernet, microSD socket and optional PoE:
... or for more program space, I/O ports consider the Freetronics EtherMega - the Arduino Mega2560-compatible with onboard Ethernet, microSD socket and optional PoE: