It's always nice with new features and enhancements but some bugs should first be fixed, like e.g. this one (i cannot update my code to a version higher than 1.5.x due to customers still using IE7):
http://bugs.jquery.com/ticket/9646
And the way these bugs get fixed is by someone spending a lot of time to track them down. As the 1.7 blog post mentions, we definitely welcome any help we can get. We are all volunteers so we don't have the time to quickly track down and fix every bug.
In the triage process we put priority on fixing the worst bugs that affect the most people. I personally triaged both #9646 and #8205 so we could mark them as verified, but tracking down and solving older-IE problems can be torture given the crude stone debugging tools available in those environments. If you have a high threshold for pain, we could certainly use your help.
I had to work around this insidious creation http://bugs.jquery.com/ticket/8205
It creates a memory leak (it hit my getJSON calls) that slowly strangled one of my apps until it crashed the browser.
I list a lot of hours on that one...