How effective is ICT in language teaching and learning?

This question has been raised on numerous occasions and few convincing arguments have been put forward that ICT makes much difference. There's a bit on ICT effectiveness here in Section 3 of Module 1.1 at the ICT4LT site:

http://www.ict4lt.org/en/en_mod1-1.htm#anchor158435

So I thought it was high time I raised this question again. Concrete evidence on the effectiveness of CALL is difficult to obtain. There is plenty of anecdotal evidence about the positive effects of CALL. Teachers often report on their students being "enthusiastic", "engaged", "motivated" and even "excited" in classes in which CALL is used, but are sceptical about measuring its effectiveness. See this summary (in Word format) of a discussion that took place in the MFL Resources forum in 2008:

http://www.ict4lt.org/en/ICT_Effectiveness.doc