Well - solving many problems is often best done by not trying to solve them at all 
Left the mystery of my 10 sec DNS lookups after scratching my head over it for a day or so.
I was a little suspicious that my home setup with a router connected to my dsl modem might have been causing problems, so I wanted to try the probes out in work. Headed in today and fired things up but got zippo hits for my dnslookup-start/done probes. Himm what was going on? Well added in an aggregate into the dnslookup-init probe to see what hosts it was asking for and turns out to be hitting "webcache.uk.sun.com", our internal web cache for all it's lookups 
Now getting out and around our webcache can require a little magic, but thanks to Daren Kenny I got a direct connection out bypassing the webcache server, thanks Darren! Now when I fired up the browser and did a little surfing to finance.yahoo.com with the browserspy script running I see the following:
DTrace Stats for: http://finance.yahoo.com
PROBE STATS:
TYPE TOTAL COUNT
DNS_REQ Network Requests - Done 14
DNS_REQ Network Requests - Started 14
DNS_LOAD Lookups - Network and Cache 23
TYPE TOTAL COUNT
URI Network Requests - Done 7
URI Network Requests - Started 8
IMAGE_REQ Network Requests - Done 37
IMAGE_REQ Network Requests - Started 37
IMAGE_LOAD Image Loads - Network and Cache 70
Browser DNS lookup requests,
PID UID STATUS COUNT AVG(msec) SUM(msec) IP HOST
1973 65535 1 1 0 0 72.14.203.91 sb.google.com
1973 65535 1 1 0 0 209.62.176.152 ad.doubleclick.net
1973 65535 1 1 293 293 69.8.201.107 ads.yimg.com
1973 65535 1 1 318 318 69.8.201.80 us.i1.yimg.com
1973 65535 1 1 325 325 69.8.201.75 us.news2.yimg.com
1973 65535 1 1 360 360 68.142.196.87 finance.yahoo.com
1973 65535 1 1 453 453 68.142.213.132 us.bc.yahoo.com
1973 65535 1 1 455 455 68.142.196.15 ichart.finance.yahoo.com
1973 65535 1 1 568 568 209.62.178.57 ad.uk.doubleclick.net
1973 65535 1 1 602 602 68.142.213.142 l.yimg.com
1973 65535 1 1 776 776 209.225.0.101 servedby.advertising.com
1973 65535 1 1 850 850 216.73.84.103 m.uk.2mdn.net
1973 65535 1 1 4223 4223 69.8.201.75 us.js2.yimg.com
1973 65535 1 1 5117 5117 216.252.106.98 streamerapi.finance.yahoo.com
:
:
Happy days It was a configuration issue, we are now seeing a much happier spread of dnslookup times. Time for me to see if I can bypass my router at home and use the dns server that the modem is using directly, should certainly make my browsing a lot faster!!
[Update]: Checked it at home changed my /etc/resolv.conf to use the netopia dsl's nameserver and all is well with the world. Now no excuse to go and get a cup of coffee, it's all so dam fast Interesting that it's a lot faster at home than at work, similar times of day as well, curious indeed, must point out to our sys admins.
DTrace Stats for: http://finance.yahoo.com from Home
PROBE STATS:
TYPE TOTAL COUNT
DNS_REQ Network Requests - Done 11
DNS_REQ Network Requests - Started 11
DNS_LOAD Lookups - Network and Cache 20
TYPE TOTAL COUNT
URI Network Requests - Done 1
URI Network Requests - Started 1
IMAGE_REQ Network Requests - Done 40
IMAGE_REQ Network Requests - Started 40
IMAGE_LOAD Image Loads - Network and Cache 71
Browser DNS lookup requests,
PID UID STATUS COUNT AVG(msec) SUM(msec) IP HOST
3237 65535 1 1 30 30 217.146.179.200 us.bc.yahoo.com
3237 65535 1 1 31 31 159.134.196.102 us.js2.yimg.com
3237 65535 1 1 43 43 159.134.196.103 l.yimg.com
3237 65535 1 1 46 46 159.134.196.118 us.i1.yimg.com
3237 65535 1 1 57 57 206.190.56.229 finance.yahoo.com
3237 65535 1 1 64 64 159.134.196.117 speed.pointroll.com
3237 65535 1 1 80 80 216.73.87.74 ad.doubleclick.net
3237 65535 1 1 98 98 159.134.196.102 us.news2.yimg.com
3237 65535 1 1 128 128 159.134.196.118 ads.yimg.com
3237 65535 1 1 161 161 72.32.153.176 ads.pointroll.com
3237 65535 1 1 652 652 206.190.56.234 ichart.finance.yahoo.com
Well the probes have their uses after all, as my friend always says when we are out hiking, trust the compass, even if you are 100% sure it can't be right, it is Unless of course you are standing on top of some lodestone, but that's another issue entirely!