I finally found the time to download a trial version of LV2012. I find that the new 2012 features are really useful and interesting. Good job NI!
One of the greatest for me is definitely the new "concatenating tunnel mode".
I've noticed that it cannot be activated with a variable of scalar type, and this obviously makes sense for almost every type of variables. However, strings are only formally scalar variable. I have lots of VI where the concatenate string vi has exactly the same use (on strings) that Build array has on numerics type of data, particularly when the concatenation had to be conditional. Obviously it is possible to convert the string into a U8 array before to connect the wire to the tunnel, and reconvert it into a string out of the loop, but this convertion probably can be internally managed without too much effort.
The attached snipped can show you what I mean. So, in my opinion, if tunnels could accept strings also when in Concatenating (conditional or not) mode would be great.