Chrome and Firefox have now rapid release cycles. Also Opera is starting to get speed and Internet Explorer should take the high road soon. I am a web developer. What does that mean for me? What consequences does it have for me? Will it be an advantage for my work or another burden?
With HTML5 being supported more fully, I would say advantageous. You will need to worry far less about feature detection (although it is still a good practice).
However, if the companies fail to perform, more errors will surely be annoying/cause more feature detection.
My 2 cents.
Advantages: browser updates are now following a push model ala Chrome so that you aren't waiting on users to go out and download the latest browser. Rapid release allows the browser developer to push new features out quicker instead of having to wait for a major update. There will soon be only one "version" of a browser.
Disadvantages: pretty much all of the above. Users behind a firewall may not be allowed to stay up to date and it will be difficult to support specific versions as version numbers ar disappearing. This means those new features may not be on your user's machine (how will you then support older "versions" when your test browser keeps updating itself?). It will also make it difficult say which versions of a browser your site will support. Testing will also be difficult as you will need to monitor all the silent updates sent to browsers and make sure your site didn't break.
One one hand, it is a good thing since new features and updated support can be pushed out in more regular cycles, rather than waiting for a big-bang type of release.
On the flip side, it means there is a greater range of support levels for different browsers - more versions of Firefox and Chrome out there. This is negated somewhat by the rapid release aspect, so browsers are more likely to be up to date.
Another possible downside, depending on how you look at it, is that the rapid releases will keep developers busy in testing the latest browser versions.
After the super buggy first release of FF4, I hope they will be able to keep up with the fast release dates, trying to release something which actually work and don't break existing websites.
To me, fastest release dates means more worries for us developers about new possible bugs and breaking existing websites, and nothing better at all.
I would prefer a full latest-standard compliant browser once in 10 years and nothing more, if you ask me.