indyank - 3:24 pm on Mar 16, 2011 (gmt 0)
aakk9999, i edited my above post, when you were probably replying to me.
I am seeing some URLs that return 404 being requested for a very long time
yes, they will, if there are links pointing to them.May be not so frequently as suggested by Tedster.
So one has to be very sure that a page neither gets search traffic not does it has good number of external links, before they decide to retun 404 or 410. If not, I would prefer a noindex, follow in such cases.You can then work on them.