Yeah, I think it was one of mine, I shall try and find it again when I have some time (next week probably), but there is also a thread on here somewhere with comments written by someone I talk to who volunteers in an animal rescue in the US, when they had to sadly make that decision for the first time in 4 years.
I also briefly read an article yesterday about people dumping more animals, if this continues to happen, things like this may become more common, cos we can't save them all. I turned down 5 cats last week, and one this week so far due to lack of space, and while I can give them other numbers, i suspect they are in the same position as us. The other option is direct homing, but if they aren't young, then they could be waiting ages - it took us nearly 2 months to home a friendly, gorgeous 2yo, because everyone wants kittens, and soo many people aren't willing to consider anything but.