One of the things I have been wishing for since I started using Google calendar and Gmail is to have a task manager. For a while I used RTP and while RTM is an excellent solution, I did not like the fact that I could not see the actual task and had to click on the RTM logo. Now that google has an integrated task manager which actually inserts the task on the calendar, I can feel whole. The experience of using this on my G1 and Iphone is extremely good.
Official Gmail Blog: Tasks, now in Calendar too: "Links"