Are you interested in updating your Windows Mobile smartphone from 6.1 to 6.5? I encourage you to review this Microsoft chart: Updating your phone to Windows Mobile 6.5 to see if your smartphone will be getting the update. The update comes from the manufacturer but it's also up to your wireless provider to release the update. Of course, you can probably find a custom ROM that's built on Windows Mobile 6.5, but it may not run very well if your hardware isn't able to support it.
Here's the link to the chart: