The new MyMusic feature lets you upload the music that you own to their servers and then stream that to your G1, PC, or Mac wherever you may be. This is handy if you do not have your music stored on your G1 or want to access that music elsewhere. Your free account includes up to 100 songs or 10 videos. You can also upgrade to VIP or VIP Plus with the VIP account priced at US$29.99/year with storage for up to 1,000 songs or 100 videos and VIP Plus for US$99.99/year for up to 20,000 songs or 500 videos. I personally have a rather small collection of songs I own and prefer to just stream my music using imeem Mobile (G1), Pandora (iPhone and Windows Mobile), or Last.fm (S60, G1, iPhone, and Windows Mobile).
The latest version of imeem Mobile also lets you create two custom Favorite stations rather than listening to the random songs when you tune into other public stations. You can also now share a song you like with your friend that will be sent via email and give them a link to the full-length song on imeem.com.
imeem Mobile on the G1 also lets you easily purchase songs you like via the DRM-free Amazon MP3 store.