OpenBSD to the rescue. I've heard CARP has been ported to FreeBSD a few months ago. Perhaps we'll see something like this in Linux sometime soon.
I've personally used LVS in a 2.6 kernel using keepalived (honestly probably the single most useful programs I've ever used, its exceptionally great software) to deploy a Mail cluster supporting SMTP/POP3 (and their SSL counterparts) in addition to Webmail over HTTP/HTTPS. It worked very well. I used dual Opteron 242's in MSI K1-1000 Chassis with a RaidZone RAID10 backend, it worked phenominally well.
SMTP, POP3, and HTTP are very forgiving protocols with respect to an LVS node going down, because people will simply either "re-check" their mail, click refresh or the software will wait long enough to be reconnected. Obviously any streaming software suffers, but this is why I mentioned CARP.