I tried the following:

@wikipedia Tamil

it gives:

Tamil may refer to:

(which is the first line and has a paragraph break after that. so it gives text until there is a paragraph break)

@wikipedia ta:AU

(which is a redirect page in Tamil Wikipedia for Astronomical Unit with a active Tamil title)

This returned text from Tamil Wikipedia page. But only numbers and english text were visible. The Tamil text was not visible even in a normally Tamil sms displaying Nokia phone. 

@wikipedia nl:Tamil

This returned the text from Dutch wikipedia :) . So the service is available for all roman letter wikipedias. 

@wikipedia ta:தமிழ்

(Page for Tamil language in Tamil Wikipedia with title in Tamil letters)

Got no response for this. So, I think the server couldn't understand non-roman letters. This phone can normally send and receive Tamil sms. 

ravi

@wikipedia ta: