I can't seem to find an official announcement, but a new beta version of Opera Mobile 8.65 for Windows Mobile is available directly from Opera's download site. This release is notable because it (finally!) includes a version for Windows Mobile 5 Smartphone devices. To install Opera Mobile on a Smartphone device: download and run opera_wm5_sp_865b.msi, then restart your phone.
Can't decide on a browser? Axim Site has a head-to-head review of Opera Mobile, Minimo and Deepfish.