Intel Haswell refresh lineup for Q2 - should I wait?

I think it is better to buy most parts as late as possible.
As new products are introduced, the tendency is to provide better price/performance.

Buying early is good if the part is not a tech heavy thing like a PSU.
Be on the lookout for a sale on Seasonic psu in the 650-750 range. They are as good as it gets, and will be able to power any foreseeable graphics card.

On graphics, buy as late as possible. The market is competitive, and if the R9-290X price ever comes down to reality, it will put price pressure on the GTX780ti cards. And.. there is a possibility that Maxwell details may emerge. At purchase time, hedge your bets with a EVGA card. They have a 90 day trade-up program where you can turn in your old card at full price on a new. I happen to like the titan stock cooler better anyhow.

New gpu's do not cause the old gpu's price to drop on the new market, only the used price drops. Vendors know that a sli/cf upgrade will need a duplicate of the old card so it can still sell at full price.
That is one of the negatives of planning for sli/cf.

If you have a case in mind, that is a ok early purchase.

I would wait on the motherboard. They do not reduce in price, but, by waiting, you will get a later bios update.

On ram you need to know the motherboard to insure compatibility.

Exactly.

The V series is one of the few top quality coolermaster psu's.

I have no problem overprovisioning a PSU a bit. Say 20%.
It will run cooler, quieter, and more efficiently in the middle third of it's range.
A PSU will only use the wattage demanded of it, regardless of it's max capability.

I might argue about planning on SLI

Here is my canned rant on planning for dual cards:
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Dual graphics cards vs. a good single card.

a) How good do you really need to be?
A single GTX650/ti or 7770 can give you good performance at 1920 x 1200 in most games.

A single GTX660 or 7850 will give you excellent performance at 1920 x 1200 in most games.
Even 2560 x 1600 will be good with lowered detail.
A single gtx690,7990, GTX780ti or R9-290X is about as good as it gets for a single card.

Only if you are looking at triple monitor gaming, or a 4k monitor, might sli/cf will be needed.
Even that is now changing with triple monitor support on top end cards and stronger single card solutions.

b) The costs for a single card are lower.
You require a less expensive motherboard; no need for sli/cf or multiple pci-e slots.
Even a ITX motherboard will do.

Your psu costs are less.
A GTX660 needs a 430w psu, even a GTX780 only needs a 575w psu.
When you add another card to the mix, plan on adding 200w to your psu requirements.

Even the most power hungry GTX690 only needs 620w, or a 7990 needs 700w.

Case cooling becomes more of an issue with dual cards.
That means a more expensive case with more and stronger fans.
You will also look at more noise.

c) Dual gpu's do not always render their half of the display in sync, causing microstuttering. It is an annoying effect.
The benefit of higher benchmark fps can be offset, particularly with lower tier cards.
Read this: http://www.tomshardware.com/reviews/radeon-geforce-stutter-crossfire,2995.html

d) dual gpu support is dependent on the driver. Not all games can benefit from dual cards.

e) dual cards up front reduces your option to get another card for an upgrade. Not that I suggest you plan for that.
It will often be the case that replacing your current card with a newer gen card will offer a better upgrade path.
The Maxwell and amd 8000 or 9000 series are due next year.
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You cant say it any better than this!!