I for one would be happy to see this. Having the market more distributed should make it much harder to manipulate.
Glad to see that happen.
However the question is if Tradehill is in a position to be trusted with the type of market share the OP is suggesting. MtGox have had and probably will continue to have a large number of technical difficulties but at least they haven't been involved in the laundering of stolen bitcoins and they're fairly clear in their TOS and communication as opposed to Tradehill, this I believe will be a serious deterrent from the more widespread adoption of Tradehill use. See https://bitcointalk.org/index.php?topic=52377.0
for more details. I had a similar issue at MtGox a couple of days ago (withdrawal not executing) 2min on IRC and the issue was resolved as opposed to this debacle.
What I'd really like to see is more growth in regional exchanges like WBX, BTCDE, BtcChina, IntersangoGBP etc... they overall provide much better
solutions (low fees etc) for their local users and are therefore growing at varying speeds.
For example BtcChina (ok not the largest exchange but still) offers more or less instant 2way funding following completion of your first in or outgoing funding @ 0.4-0.5% in fees. This is a feature that most other exchanges would kill for just imagine being able to sell coins then being able to spend the cash within minutes on your credit/debitcard.