We used to use google perftools at work - for hooking malloc, etc, and other things (general memory manager replacement). It used to work fine, until it start breaking on some Win Server machine (one of 100+ machines). We did not have time to find whether there is fix for it.
Also we had an idea of replacing perl that was embedded in one of our tools with JavaScript (V8) but the programmer that did that left just after finishing it, and without support we decided to stay with Perl.
I looked at about 10 of these that I hadn't seen before, and they're all either google-foo projects or their developers have @google.com email addresses.
There is a higher level for official Products and hosted APIs where there is a full-fledged team behind it and a much higher level of support. Instead of being labeled projects, they have top level sites:
Also we had an idea of replacing perl that was embedded in one of our tools with JavaScript (V8) but the programmer that did that left just after finishing it, and without support we decided to stay with Perl.