In the case of Maverick 10.10, that doesn't matter too much, as it reaches its own EOL in April 2012 too, but Lucid 10.04 is an LTS release and will reach its EOL only in April 2013 (Desktop; Server in 2015), so they were compelled to do this.
Please also see this official doc:
And you can check the current status of the Firefox packages in the official repos by visiting this site:
Update 1/27/2012: The Firefox 9 packages have now eventually arrived in the official repos of both Lucid 10.04 and Maverick 10.10.
Update 1/29/2012: Chris Coulson, the maintainer of the "Firefox Stable PPA", announces on his blog that he's going to retire that PPA due to matter of this post, which makes completely sense, of course.
First off, if you weren't already using a PPA to get the latest versions of Firefox, or installed them manually, you'll get all the new features and improvements since the release of Firefox 3.6, which is huge leap forward! And also, this will lift Firefox back on par with Chromium, which was updated in the official repos throughout all the time.
On the other hand, some IT departments of enterprises using Ubuntu 10.04 LTS might not be so happy with this, since the rapid release cycle of Firefox in general is already drawing a lot of criticism since its introduction, particularly from that corner. That's because every new version can bring some regressions and backward compatibility issues with it, of course, and enterprises, if acting responsible, need to test them before rolling out the upgrade.
However, I can imagine that Canonical will later on switch at least the LTS (Long Term Support) versions of Ubuntu to using the recently announced ESR (Extended Support Release) versions of Firefox, planned to start with Firefox 10, and currently scheduled for a life-cycle of 54 weeks (derived from 9 release cycles of the regular version). ... I mean, hopefully they would apply that only to the LTS versions, as otherwise, the average user - usually going along with the regular versions - would miss out all the latest features and improvements introduced to Firefox.
Update 2/7/2012: Chris Coulson, maintainer of the Firefox packages, outlines on his blog the pros and cons, and the prospects of offering the Firefox ESR version via the official repos or a PPA - the bottom line: as of now, not planned via the official repos; but maybe via a PPA, I suppose depending on the demand.
Digging more into the above-mentioned possible backward compatibility issues, every new version of Firefox is likely to break one or more add-ons you might have installed, when the most recent available version of it is either really not compatible with the new Firefox version, or is simply not marked as such. Depending on what's the case, you either need to manually mark it as compatible, or find an adequate replacement for it.
Well, that depends on if you were till now using a PPA - usually the "Firefox Stable PPA" - to get the latest versions of Firefox, or not:
- If you were using the "Firefox Stable PPA" till now, due to the fact that it will be retired now (see above), you should disable it in your "Software Sources > Other Software", and let the next update to the official repos switch you over to them.
- If you are using any other PPA or repository, you can leave it enabled if you think you'll get the updates more quickly, or in the case of the "Firefox Next PPA", you would keep on getting the versions currently in Beta stage.
- If you weren't using any PPA or repository so far, to get the current Firefox releases (!), you don't have to do anything, just let the next update upgrade you, and enjoy!
However, as mentioned above, it might be that one or more add-ons you have installed aren't compatible with the new version of Firefox, or simply aren't marked as such. To check if the latter is the case, and by that also fix it, manually modify the respective version entry in the add-on's "install.rdf"; you'll find it in the top-level directory of the add-on, in the "extensions" directory of your Firefox profile (if installed as .xpi file, just open that with the Archive Manager, and modify the "install.rdf" from inside it).
Update 1/31/2012: Starting with Firefox 10, this manually fixing shouldn't be necessary anymore (yay!), as all add-ons are now considered to be compatible by default, even if they aren't marked as such.
Well, the version currently maintained in the official repos is Thunderbird 3.1, and till now there is no indication when it will stop receiving security updates, thus when its EOL will be. So there seems to be no imminent change in that regard. That means if you want to get the latest versions of Thunderbird for your Lucid 10.04 or Maverick 10.10 installation, you still need to use a PPA for that, for example, the "Thunderbird Stable PPA" (btw., the same applies to Natty 11.04). For details on how to use it, please see this recent post: