I have, many times in the last 2 or 3 years... I still do... It's cheap and easy to implement, it's easy to use and it ads just as much cruft as I'm willing to tolerate. I build boring software, average CRUD applications for government departments, people in this line of work don't give a shit about millisecond delays or reactivity, hell, they don't even care about responsiveness... jQuery facilitates high speed development, provides neat functionality that doesn't get in the way, it's easy to maintain, and keeps people happy.