Among all the 5.0 leaks people seem to forget there will still be carrier releases along the way. The latest offering is OS 18.104.22.1685 for the Curve 8520 from T-Mobile UK. This is an official OS, so if you didn't make the jump to 5.0 this past week, you may want to check it out. You can grab it from the T-Mobile UK download site.
Best in class:Save 49% on 15 months of ExpressVPN