It's sometimes said that anime songs are sung by seiyuu, by singers just starting their careers, or by singers on the downslide. And TV drama songs are by stars at their peak.
That rule of thumb may not always be true, but it is true of the good new drama Last Friends. Its OP, "Prisoner of Love," is sung by Utada Hikaru. The visuals are great, too, featuring the stars of the dorama: big-name stars including Nagasawa Masami and the wonderful Ueno Juri, who was Nodame in the drama version of Nodame Cantabile.
Last Friends is currently running fifth in the top ten drama ratings, with almost 16% of the audience in its 10 p.m. Thursday timeslot. That's higher than the top-rated anime (Sazae-san is at 14.4%), and five times the ratings of top late-night anime. For more info and to find out how to see the show, check D-Addicts. There is a full wiki here outlining the plot. Be prepared for plenty of angst.
Several people are blogging the show. You can find some entries on Anime Nano.