You will probably start to see most droid phones getting OS updates at the end of sept/oct after all the new driod phones are released for the back to school phase. I believe the Spica update to 2.1 is dropping at the end of this month so its just a matter of time before old devices are updated.
Sony Ericsson has stated that 2.1 will be released in Q3 2010 which means either this month or next. With Sony, that usually means right near the end of the deadline, so most likely September.
There are a few videos of 2.1 running on the Xperia X10 on youtube which look pretty nice. The curved slide to unlock has been replaced with a more traditional lock screen. Other than that there don't seem to be many cosmetic changes.
The problem with the update process is that even with SE releasing 2.1 in September or even this month (not likely) is that Rogers has to be the one to actually give it the stamp of approval and roll it out. To put this into perspective, since the last update to the 020 firmware, SE has released 6 additional patches which we have not seen. We'll see how they handle a major update, but so far I'm not too optimistic.
Every major update has its problems, I remember a couple with the iPhone that were usually fixed within a day or two, at first there will be some reliability issues but it should be fine.
Rogers has zero say in the availability of iOS patches. Those are released by Apple and not through a carrier or with the carriers approval, which is the proper way to do things.
Im not sure when you got the X10, but there was a patch released back in July for the X10 that helps with battery life and otherwise general performance. You can go to www.sonyericsson.com/updateservice for the latest software and updates, but be sure to back up anything you cant afford to lose. Here is a walkthrough http://www.youtube.com/watch?v=SdlT4VHim0c for doing it right over the phone.
My money is on SE to release it late September and for Rogers to push it out late October. Keep in mind that we never received the R2BA016 update and we received the R2BA020 update weeks after European and Asian providers.
014 -> 020
As far as I can tell this is how it was for all Rogers devices. Perhaps SE shipped some more recent devices with 016 installed by default, but I never had the option to update to that.
SE has already stated that the X10 will be updated to 2.2 on their product blog. I'm hoping that 3.0 will also be supported. After this Google should be implementing their one major update a year scheme so it will give these phones a pretty long support life.