No it's not, unless you manage to reformulate the address change as a real question. If the site is yours you can add the address to your profile. And of course you can add it here as a comment to this same question nevertheless. If the site is useful you will probably find other questions on BioStar where mentioning the site could be part of a valid answer.

Some questions you can try:

• Does anyone know how to use site x, or what to use it for (answering it yourself might be a good idea)
• What new features would you want for site x (btw the new address is...)

Ohh and technically this is not a correct question either. Since people will argue that it is a meta question and belongs in the user group (see the link at the botom of each page). But I guess if you knew that you would never have asked ;-)

Ohh and just thought of something else. You could also ask a new question" Which bioinformatics websites got new addresses recently?" That is a valid question (well, sort of), and you could answer it with the information you want to provide. Even better anyone announcing such a change in the future could answer the same question

You can try to post you announcement at http://seqanswers.com/

which is an active community for next generation sequencing technology. It has a sub-section named Bioinformatics.

Twitter. It is a great medium of sharing updates. In return you will get an impression how much your service/website is appreciated.

If only the IP is changed, you can modify the DNS to resolve your domain name to your new IP.