Compact cranks use a 110mm spider to accommodate a smaller inner chainring.  This allows you to gear almost as low as you would using a triple with a 30-tooth inside chainring.  The 34-28 combination allowed by SRAM's 11-12-13-14-15-17-19-22-25-28 cassette is very close to a 30-25 with a triple crankset.  The compact crank typically comes in a 50-36 or 50-34 combination.  Compare high and low gears with your typical double or triple in the following chart: 

Gear Roll-Out (inches)
		50		36		34		53		52		39		30
11		119.5		86.0		81.2		126.6		124.2		93.2		71.7		11
12		109.5		78.8		74.5		116.1		113.9		85.4		65.7		12
13		101.1		72.8		68.7		107.1		105.1		78.8		60.6		13
14		93.9		67.6		63.8		99.5		97.6		73.2		56.3		14
15		87.6		63.1		59.6		92.9		91.1		68.3		52.6		15
16		82.1		59.1		55.8		87.1		85.4		64.1		49.3		16
17		77.3		55.7		52.6		81.9		80.4		60.3		46.4		17
19		69.2		49.8		47.0		73.3		71.9		53.9		41.1		19
21		62.5		45.1		42.5		66.3		65.1		48.8		37.5		21
23		57.1		41.1		38.8		60.6		59.4		44.6		34.3		23
25		53.5		38.5		36.4		56.8		55.7		41.8		32.2		25
27		50.0		36.0		34.0		53.0		52.0		39.0		30.0		27

The Bike Center can:

	Upgrade your current system to a compact crankset
	Order you a complete bike that comes stock with compact cranks
	Build you a custom Lynskey with compact cranks

How well will a 50-34 work?  The newer cranks with this chainring combination seem to have worked the kinks out of earlier 50-34s, which didn't always function well with 10spd drive trains.  Campy has a compact-specific front derailleur specifically designed to handle more than a 14-tooth difference in chainring sizes.  FSA makes a compact-specific front derailleur that works well with Shimano and SRAM drive trains.

Is the compact viable for racing?  Division I pros are using compact cranks in the mountains in major stage races in Europe.  If the pros can successfully use a compact for racing, so can you.  If you feel undergeared with a 50-34, try a 52-36 or 52-38.