Today, I saw a thread where Google warned against using the NOSCRIPT tag.
Googler, JohnMu, said in a thread, "the problems with noscript is that it's been abused quite a bit by spammers, so search engines might treat it with some suspicion." In fact, in 2006 Brett Tabke said links in noscript tags didn't pass PageRank.
JohnMu actually offered it as an alternative for one webmaster, saying, "I imagine the use of a noscript element in the way you are using it might be a fairly safe compromise." But then went on to say that search engines are suspicious when it is used. Let me quote John fully:
Failing that, I imagine the use of a noscript element in the way you are using it might be a fairly safe compromise. One of the problems with noscript is - as others have mentioned - that it's been abused quite a bit by spammers, so search engines might treat it with some suspicion. So if this is really important content, then I wouldn't rely on all search engines treating your noscript elements in the same way as normal, visible, static content on your pages. If this is "just" for comments, then that might be worth considering regardless, especially if the alternatives are much more complicated.
So be careful when using this and try everything you can do avoid it.
Forum discussion at Google Webmaster Help.