I tried to send my friend a quick note since I hate typing out text messages on my phone and discovered that the service had been closed.
http://www.google.com/tools/firefox/sendtophone/

What a bummer.

After almost two years of service, we came to realize that it was only another fail. I believe that it was terminated two days ago, on August 4, '08.

Google Maps still has it though you can't (unless you figure out a way) send whatever you want.

Consider the alternative:
http://en.wikipedia.org/wiki/SMS_gateway#Carrier_Provided_Email_or_Web_to_SMS_gateways

Really though, it isn't hard to roll out your own with multi-nations/carriers support.

I use Gmail to Txt every single day. It's great. The keyboard shortcuts make it very nice.

Yeah, the only benefit of Google Sent to Phone was that you didn't have to know the carrier and the domain, just the number.

You NEED to know the carrier.
http://www.google.com/tools/firefox/sendtophone/faq.html#q5

Anyway, I wrote a small script that does the job (currently supporting major US wireless telecoms) and you don't need to know the carrier (oh err, I just send an email to each one of the carrier).
http://ihaochi.com/sms.php

{ Fake edit: ehh, just found out there are also similar/better services out there... i.e: http://gizmosms.com/ }

OT: When did you add that "rules & formatting" here, Philipp?

> OT: When did you add that "rules & formatting" here, Philipp?

Just yesterday I believe, thereby breaking the submit button. Ouch.