When attempting to enter a set of keywords when creating or duplicating pages, the system generates a return code error, the issue was reproduceable on both IE and FireFox and it seems to be related to a maximum number of characters that the system can handle, IE returns error code 12031 while FireFox returns error code 0. I have attached screenshots of the issues we are getting, please let us if anyone had seen the issue and has a workaround for it. I have noticed another thread http://www.sitefinity.com/devnet/forums/sitefinity-4-x/bugs-issues/return-code-12031.aspx which discusses a maximum length of 255 for description so we might have the same issue for keywords but that was before the 4.1 release and we are also getting different codes between IE and FireFox.
We don't believe this is a problem - by good SEO practices, the keywords should be around 30 to 180 characters. Everything beyond this length will be probably stripped by the search engines. Even if we increase the limit and you put more keywords, this won't have any effect on your web site SEO performance.